In the battle between the GOP establishment and the tea party, Thom Tillis' nomination for the U.S. Senate seat from North Carolina scored a win for party elders who are trying to exert control over the elections and wrest the chamber from Democrats.

But "establishment" is a relative term these days. The GOP's internal divisions have pushed the whole Republican Party to the right. As speaker of the state House at a time when the Tar Heel State's GOP took a hard right turn, it remains to be seen how much Tillis is in the Republican mainstream.

Defining both Tillis and his opponent in November — vulnerable Democratic Sen. Kay Hagan — will become a high-stakes war of words in what could become the most politically brutal and costly Senate race.

Tillis launched his general election bid Wednesday by labeling Hagan a "rubber stamp for President Obama's liberal agenda."

Hagan's campaign distributed a dossier on Tillis' "fringe" positions as they prepared to battle the candidate whose "special interests," it said, "are dragging him across the finish line."

North Carolina was a focal point in this week's primary elections, which also saw "American Idol" star Clay Aiken's surprise emergence as the likely Democratic nominee in a long-shot bid for a House seat in suburban Raleigh.

Aiken ran an underwhelming campaign, but the sheer force of his celebrity status appeared to edge out a candidate preferred by party officials, former state commerce secretary Keith Crisco. Aiken led Crisco by fewer than 400 votes in a race that remained too close to call late Wednesday. A candidate must clear 40% of the vote to avoid a July runoff.

The southwestern Raleigh district was carved to be a GOP stronghold. Aiken, who grew up in the area, faces tough odds of winning in November against Rep. Renee Ellmers, especially in a region that may be skeptical of his connection to Hollywood.

Statewide, however, North Carolina remains decidedly purple. And that makes the fight for the Senate so close that the nonpartisan Rothenberg Political Report labeled it a toss-up after Tillis' victory.

Tillis won backing from a chorus of Republican leaders, including former GOP presidential candidate Mitt Romney and the U.S. Chamber of Commerce, which preferred his legislative record to the absence of one from conservative newcomer Greg Brannon.

Brannon, who grew up in Inglewood and graduated from USC, was a tea party favorite from outside the political system — a gynecologist and father of seven with a libertarian streak who was backed by Republican Sen. Rand Paul of Kentucky.

Paul and other tea party leaders called for unity after Brannon's defeat. "We obviously aren't happy with the outcome," said Jenny Beth Martin with the Tea Party Patriots Citizens Fund.

As is happening elsewhere in Senate races, the hard-line GOP candidates are being brushed back by an onslaught of support from the establishment. Party leaders are trying to prevent expensive runoffs and avoid nominating extreme candidates who could dash GOP hopes of gaining the six seats they need to retake control of the Senate. Karl Rove's American Crossroads swooped in to back Tillis.

Tillis, though, is hardly a bipartisan pragmatist in the old-school GOP style. He is a conservative leader who, according to his campaign, wants to "shrink" government, believes "the traditional family is the bedrock of America's culture" and calls Obamacare a "cancer" that needs to be repealed.

Under his watch, the North Carolina statehouse has enacted strict voting laws and refused to expand Medicaid under Obama's Affordable Care Act, partly giving rise to the "Moral Mondays" protest movement by the NAACP that has spread across the South.

"Thom Tillis helped lead a conservative revolution in NC and he will do the same in Washington," his wife, Susan Tillis, said on Twitter on election day.

Hagan's team is recycling comments Tillis made about the need to "divide and conquer" the poor, tying him to Romney's dismissive remarks during the 2012 campaign about the 47% of Americans who he said pay no federal income taxes.

"What we have to do is find a way to divide and conquer the people who are on assistance," Tillis said in a 2011 video circulated by the Hagan campaign. "We need to get those folks to look down at these people who choose to get into a condition that makes them dependent on the government and say, 'At some point, you're on your own. We may end up taking care of those babies, but we're not going to take care of you.'"

Tillis said Wednesday during an interview on MSNBC that he regretted the phrasing, and meant only that government aid should be reserved for those truly in need.

The fight is bound to become rough. Outside groups led by Americans for Prosperity, which is aligned with the billionaire industrialist Koch brothers, has already poured in more than $7 million to attack Hagan's record. The Democrats' Senate Majority PAC has spent almost half as much.

In an email to supporters after he won the party nomination Tuesday, Tillis seemed up for the fight, saying: "It begins tonight."

lisa.mascaro@latimes.com