Battling for his political survival, six-term Sen. Thad Cochran narrowly led tea party favorite Chris McDaniel Tuesday night in a bruising, costly Mississippi primary runoff that showed deep divisions within the Republican Party.

With nearly 79 percent of the precincts reporting, Cochran led with 51 percent of the vote to McDaniel’s 49 percent.

The veteran lawmaker and his allies had highlighted his seniority and Washington clout in the three-week dash since an inconclusive June 3 primary, while McDaniel had argued that Cochran was part of a Washington blight of federal overspending.

In a last-ditch effort, Cochran had reached out to traditionally Democratic voters — blacks and union members — in his race against McDaniel. Voters who cast ballots in the earlier Democratic primary were barred from participating.

The Mississippi contest that threatened to cast aside the 76-year-old Cochran was the marquee race on a busy June primary day that included New York, Oklahoma, Colorado, Maryland and Utah.

In a blow to the tea party movement, two-term Rep. James Lankford of Oklahoma won the GOP nomination in the race to succeed Sen. Tom Coburn, who is stepping down with two years left in his term. In the solidly Republican state, Lankford is all but assured of becoming the next senator.

A member of the House GOP leadership, Lankford defeated T.W. Shannon,, a member of the Chickasaw Nation and the state’s first black House speaker. National tea party groups and the Senate Conservatives Fund had backed Shannon, who also had the support of Sarah Palin and Texas Sen. Ted Cruz.

In New York’s Harlem and upper Manhattan, 84-year-old Democratic Rep. Charles Rangel, a 22-term congressman and the third-most-senior member of the House, faced a rematch against state Sen. Adriano Espaillat, bidding to become the first Dominican-American member of Congress.

Rangel, one of the founders of the Congressional Black Caucus, drew criticism last month when he dismissed the 59-year-old Espaillat as a candidate whose only accomplishment was to be a Dominican in a majority Latino district.

Two years ago, Rangel prevailed in the primary by fewer than 1,100 votes.

Despite Congress’ abysmal public approval ratings, incumbents have largely prevailed midway through the primary season — with two notable exceptions.

Little-known college professor Dave Brat knocked out House Majority Leader Eric Cantor in Virginia’s Republican primary this month, and Republican Rep. Ralph Hall, 91, lost in a Texas runoff to a younger Republican.

McDaniel declared as he voted Tuesday, “We are here, we’re going to fight for our belief system, no matter what, and we’re going to reclaim Washington, D.C., one race at a time.”

Cochran and his allies, including former Gov. Haley Barbour, highlighted his decades on the Appropriations Committee and his work directing billions in federal dollars to his home state, one of the poorest in the nation.

That resonated with Jeanette Tibbetts, a 73-year-old retiree.

“I’m a ninth-generation Mississippian. … How can you live in south Mississippi and not see Thad’s evidence?” asked Tibbetts, who voted in Hattiesburg on Tuesday.

Kellie Phipps, a 42-year-old public school teacher from Taylorsville, voted for McDaniel. “I think we need some new blood,” Phipps said.

The Cochran appeal to non-Republicans infuriated McDaniel and prompted tea party groups — as well as the NAACP and the Justice Department — to keep tabs on who was voting in Mississippi. State officials also were observing the voting.

Officials said more absentee ballots had been requested for Tuesday’s elections than the June 3 first round of voting, suggesting turnout might be heavier thanks to outside groups’ efforts to motivate allies. McDaniel finished first in that round, but he was short of the majority needed for nomination.

Outside groups, from tea party organizations to the U.S. Chamber of Commerce, have spent some $12 million on the race. Former Green Bay Packers quarterback — and Gulfport, Mississippi, native — Brett Favre called the 76-year-old Cochran a “proven and respected leader” in one Chamber ad.

McDaniel, 41, an attorney and former radio host, has the strong backing of former vice presidential candidate Sarah Palin and the tea party movement, which sees his political approach as a change from a Washington status quo of mainstream conservatives willing to compromise.

In the campaign, McDaniel has had to distance himself from past controversial remarks that he uttered about Hispanics and blacks on his radio broadcast.

The runoff winner will face Democrat Travis Childers, a former congressman, in the heavily Republican state.