Mississippi Sen. Thad Cochran and insurgent challenger state Sen. Chris McDaniel were locked in a tight battle as the votes were being counted late into the night here in the marquee Republican Senate primary race of the night Tuesday.

The six-term incumbent faced the real possibility of being forced into a politically perilous run-off June 24 as the result could have a major impact on Republican hopes of recapturing the Senate in November.

To win the nomination outright, a candidate needed to secure 50 percent of the vote. With 86 percent of the precincts reporting late Tuesday evening, Mr. Cochran trailed with 48.4 percent to 50.0 percent for Mr. McDaniel, with a third candidate taking the rest.

Mr. Cochran’s supporters hoped the incumbent could hang on for an outright win, fearing that a runoff later this month would favor his tea party-backed opponent.

The winner of the runoff will face former Rep. Travis Childers, who easily won the Democratic nomination and could benefit from an extended battle on the Republican side.

Ford O’Connnell, a Washington-based GOP consultant, said that Mr. McDaniel sent a message with his strong showing.

“Cochran has thrown everything at McDaniel including the kitchen sink and there is no question McDaniel is standing his ground,” Mr. O’Connell said. “Without Rose-gate this might likely already be over, because it increased turnout.”

Mr. O’Connell also said that Democrats are looking to expand the map wherever they can and are more likely to invest in the race if Mr. McDaniel wins the race.

“They are going to look for every opportunity they can to try to force Republicans to pick up seven seats,” he said. “So they could start to marshal resources if McDaniel won, but it is still a long shot even if McDaniel is the nominee.”

Read more from Seth McLaughlin at The Washington Times

From Ross Ramsey at The Texas Tribune:

Texas’ Republican primary for U.S. Senate is close — and could be headed for a July 31 runoff — with Lt. Gov. David Dewhurst holding a single-digit lead over former Solicitor General Ted Cruz, according to the latest University of Texas/Texas Tribune poll.

Dewhurst had the support of 40 percent of likely voters, followed by Cruz at 31 percent. Former Dallas Mayor Tom Leppert had 17 percent and broadcaster and former football player Craig James was at 4 percent, with five other GOP candidates bringing up the rear.

Daron Shaw, a UT-Austin government professor and co-director of the poll, said Cruz has been able to position himself to the right of the lieutenant governor for a May 29 Republican primary where that's a big advantage — and he's done that in a year in which insurgent candidates have been scoring big wins against establishment Republicans.

After what happened in Nevada and now in Minnesota, Team Romney is probably suffering some heartburn. The Minneapolis Star Tribune has more:

After years of quiet, relentless organizing, followers of libertarian-leaning GOP presidential candidate Ron Paul have exploded inside the Minnesota Republican Party, becoming its most potent army.

"This is one of the greatest states that I have witnessed, where I have seen the transition, where the enthusiasm's there," the grinning Texas congressman told hundreds of exuberant activists Saturday at the state party's convention in St. Cloud, where he won 12 of 13 open delegate spots to the GOP national convention in Tampa, Fla., in August. The 13th went to former presidential candidate and U.S. Rep. Michele Bachmann -- and only after a Paul supporter dropped out to let her have that spot.

In Minnesota, more than almost any other state, Paul forces have completed a historic party takeover. They proved their might Saturday, but also firmly established Minnesota as a remote GOP outpost nationally.

Now state GOP activists will march to the national convention firmly backing Paul rather than presumed Republican presidential nominee Mitt Romney.

Republican presidential candidate Ron Paul effectively ended his White House bid on Monday, saying he would no longer campaign actively in states that have yet to hold primary elections.

Instead, Paul's campaign will concentrate on trying to add to its tally of delegates to the Republican National Convention in August by sending large groups of supporters to state conventions to elect themselves to delegate slots.

Paul is the last main challenger to presumptive nominee Mitt Romney in the race to pick a Republican candidate to confront President Barack Obama in the November 6 election.

Paul has not won any state nominating contests. So far, he has only 99 delegates while Romney has 949, according to Real Clear Politics. A candidate needs 1,144 to win the nomination.

Republican strategist Ford O'Connell said Paul's new plan will not change much in terms of campaigning since he was spending very little time on the campaign trail compared to candidates like Romney.

"Obviously he still wants to be a fly in the ointment, particularly for Romney, he just doesn't want to be running the negative ads," said O'Connell.

"Romney is in a very tight battle with President Obama," said O'Connell. "He needs to have all hands on deck to beat Obama and everything has to go right - he really does not need to be looking over his shoulder at Ron Paul."

Read more from Deborah Charles at Reuters

Very solid analysis. From NBC's First Read:

(1) Residency and outreach: Lugar hasn’t lived in Indiana for years and wasn’t able to say what address was on his driver’s license. Mourdock exploited it. And Lugar didn’t do enough outreach with local GOP establishment or Tea Party leaders. Lugar disputes that, telling NBC’s Kelly O’Donnell: “I've been perfectly connected all the way along. It’s a ridiculous charge. How can anybody be more Hoosier? I've got a farm out here that I continue to work with my sons. I manage it on behalf of our family. I'm in touch every week with everybody in the state, usually on the ground with visits but with our staffs, trying to meet almost every challenge of individual Hoosiers or groups.”

(2) Ignoring the recent past: Last year, Republicans walked Lugar through what went wrong with Bennett, Lisa Murkowski, and Mike Castle. And what went right with John McCain -- no favorite of the Tea Party – who went after opponent J.D. Hayworth early on and never let up. Unfortunately for Lugar, strategists say, the advice was ignored. If you don’t want to change your own stances, then make the alternative unacceptable. McCain made his alternative unacceptable.

(3) Campaign: he didn’t have the kind of campaign in place that was necessary to win this kind of race. Hatch and even Olympia Snowe got it, and hired top operatives. Mourdock hired people who’d been there before;

(4) Message: “Lugar as statesman” just wasn’t going to get the job done. Movements have short-term memories. Mourdock’s message was simple and effective– “Dick Lugar is a fine man, but 36 years in Washington is long enough, and he’s lost touch with Indiana.”;

(5) Candidate: So much of what happens in campaigns, comes from the top. As revered as Lugar is in Washington, he wasn’t able to adapt -- and failed to fully appreciate -- a changing dynamic within his party. Yesterday, for example, he continued to defend earmarks.  

It came at 11 p.m. Monday, in the 13th paragraph of an e-mail to supporters: Rick Santorum’s endorsement of Mitt Romney.

Former Senator Santorum, whose passionate advocacy for conservatism contrasted sharply with Mr. Romney’s more moderate persona, dropped out of the presidential race nearly a month ago, on April 10, ceding the Republican nomination to Romney.

“Above all else, we both agree that President Obama must be defeated,” Santorum wrote Monday. “The task will not be easy. It will require all hands on deck if our nominee is to be victorious. Governor Romney will be that nominee and he has my endorsement and support to win this, the most critical election of our lifetime.”

To sum up his message: At least Romney is better than Mr. Obama.

Santorum’s tepid nod to Romney “shows his reluctance to be fully on board,” says Terry Madonna, a political scientist at Franklin & Marshall College in Lancaster, Pa. “It shows that he still harbors this concern that Romney isn’t a true conservative."

If Romney wants more out of Santorum, he’s going to have to deliver, says one Republican strategist.

“I think that Santorum knows that Romney’s going to need social conservatives, so right now [Santorum] is a valuable commodity,” says Ford O’Connell, chairman of Civic Forum PAC. What Santorum wants, he adds, is a prime-time speaking slot at the Republican convention in August.

Read more from Linda Feldmann at The Christian Science Monitor

Mitt Romney will likely need Rick Santorum's assistance on the campaign trail as a conduit for social conservatives. If Romney is to defeat Obama in November, all Republicans will have to be moving in lockstep. ABC News has more on Santorum's endorsement:

Rick Santorum has officially endorsed Mitt Romney, and notified his supporters in an email sent Monday night.

In the lengthy email, Santorum encouraged Romney to “add more conservative leaders as an integral part of his team.”

“And you can be sure that I will work with the governor to help him in this task to ensure he has a strong team that will support him in his conservative policy initiatives,” Santorum said.

Santorum told his supporters he intends to “keep lines of communication open.”

“Above all else, we both agree that President Obama must be defeated,” the letter read. “The task will not be easy. It will require all hands on deck if our nominee is to be victorious. Governor Romney will be that nominee and he has my endorsement and support to win this the most critical election of our lifetime.”

Click here for the full text of Santorum's endorsement

From Ken Walsh At U.S. News & World Report:

Republican presidential candidate Ron Paul's hard-nosed troops aren't giving up. Far from it. As demonstrated anew last weekend in Nevada and Maine, they are shaking up the GOP establishment and causing discomfort to strategists for front-runner Mitt Romney by capturing delegate blocs at the state level as they prepare for the Republican National Convention in Tampa this summer.

Paul organizers won't tell the media exactly what they will do in Tampa or which states they will target next. And they have many challenges. For example, party rules often require national delegates to support the winner of state-level contests on the first ballot. So even though newly selected delegates in Nevada, Maine and elsewhere might personally back Paul, they could be bound to vote for Romney on the initial roll-call vote. But there is an alternative scenario. Paul strategists tell me that a delegate is permitted to abstain on the first ballot, which could conceivably deny Romney the nomination if enough of them go that route, combined with those still committed to candidates who have dropped out.

There is a strong desire among Paul supporters at the grass roots to push as hard as they can to put his name formally into nomination. They want him to address the convention in prime time and make his libertarian case directly to the nation. They also want to exert an influence on the party platform.

Romney still has 856 delegates, 288 short of the 1,144 needed for the nomination, according to an Associated Press count.

Romney is expected to reach 1,144 and clinch the nomination later this month or in early June, unless Ron Paul's cadres pull off a historic upset.

Newt Gingrich ended his run for U.S. president on Wednesday after dazzling in televised debates but slumping to defeat in dozens of Republican primaries under attack from rivals who portrayed him as the consummate Washington insider.

The former U.S. House of Representatives speaker, the face of the Republican Party in the mid-1990s, badly trailed front-runner Mitt Romney in polls and his campaign piled up a debt of $4.3 million.

Gingrich announced his departure from the White House race in a long statement to the media at a hotel in Arlington, Virginia outside the capital that included references to his many grandiose ideas like the establishment of a U.S. colony on the moon.

He fell short of endorsing his former rival Romney but said voters had a clear choice in November's general election between Democratic President Barack Obama and the former Massachusetts governor.

Republican strategist Ford O'Connell said Gingrich will quickly be back on the campaign trail, likely as an "attack dog" for the Republican Party as it seeks to unseat Obama.

"The GOP needs him. They need conservative attack dogs who can break up the Obama message machine," said O'Connell. "He has the ability to take complex items and boil them down to be palatable Kool-Aid for conservatives."

"He's one of the best messengers of the right who, on a moment's notice can rebut someone."

Read more from Deborah Charles at Reuters