A slew of May primary battles begins Tuesday as the Republican establishment looks to reassert its control over a divided GOP in a number of states.

Its first big test comes in North Carolina, where business-friendly GOP groups have gone all-in for House Speaker Thom Tillis as he seeks to avoid a primary election runoff and turn his focus to Sen. Kay HaganKay Ruthven HaganNC state senator meets with DSCC as Dems eye challenge to Tillis GOP, Dems locked in fight over North Carolina fraud probe 2020 Dems compete for top campaign operatives MORE (D-N.C.). The race is a top priority for the GOP as it seeks to win back the Senate.


The U.S. Chamber of Commerce and American Crossroads have combined to spend nearly $2.5 million on ads boosting Tillis in the race, deluging the airwaves to raise his name identification. Former GOP presidential nominee Mitt Romney endorsed Tillis on Monday, joining former Florida Gov. Jeb Bush (R) and North Carolina Gov. Pat McCrory (R).

As the TV battle heated up, Tillis rose quickly on the polls and is now on the cusp of the 40 percent he needs to win the primary on the first try, according to recent public and private polling. If he falls below that mark he’ll have to contend with a mid-July primary runoff against either Tea Party candidate Greg Brannon (R), who is campaigning with Sen. Rand PaulRandal (Rand) Howard PaulHillicon Valley: Mueller delivers report, ending investigation | FEMA exposed info of 2.3M disaster survivors | Facebook asks judge to toss DC privacy lawsuit | Trump picks his first CTO | FCC settles lawsuit over net neutrality records Transparency advocate says government agencies face 'use it or lose it' spending Republicans need solutions on environment too MORE (R-Ky.) on Monday, or Rev. Mark Harris (R), who has former Arkansas Gov. Mike Huckabee’s (R) support.

A win on Tuesday allows Tillis to conserve resources for the general election and train his fire on Hagan, who has had a narrow lead against Tillis in most recent public polls. But if he falls short he’ll have to slog it out for another few months, potentially hurting his chances in the general election and giving the Tea Party another shot. 

“It’s extremely important. If Tillis avoids a runoff the headline is ‘GOP dodges a bullet’ and if he doesn’t, it’s ‘Hagan dodges a bullet,’ ”  said Republican strategist Ford O’Connell. 

O’Connell said the race could help set the tone for the rest of the primary season, for better or worse.

“It’s important for Tillis to get the party beyond this hump psychologically as well. It could make a lot of other things go easier. The last thing the party wants is the ‘here they go again’ narrative,” he said.

In the eastern end of the state, establishment Republicans face a tough challenge in defeating Rep. Walter Jones, an iconoclastic Republican who’s been a regular thorn in the side of GOP leaders. He’s facing Taylor Griffin, a former Treasury official during George W. Bush’s administration who has backing from many establishment Republicans. Griffin has also been endorsed by former Alaska Gov. Sarah Palin (R), whom he worked for while on Sen. John McCainJohn Sidney McCainGraham: McCain 'acted appropriately' by handing Steele dossier to FBI What should Democrats do next, after Mueller's report? Tom Daschle: McCain was a model to be emulated, not criticized MORE’s (R-Ariz.) presidential campaign.

Unlike other establishment targets, Jones has angered his party’s leadership for his dovish foreign policy views and populist fiscal stances, including a vote for Democrats’ Wall Street reform law.  

Center-right groups are also playing in the race for retiring Rep. Mike McIntyre’s (D-N.C.) seat, a likely GOP pickup regardless of the primary’s outcome. The U.S. Chamber of Commerce has spent $300,000 on ads attacking Tea Party candidate Woody White, while the American Action Network and YG Network are running radio ads attacking him and boosting his opponent, former state Sen. David Rouzer, who fell just short against McIntyre in 2012. 

Easier tests for the GOP establishment come in Ohio.

Speaker John BoehnerJohn Andrew BoehnerBoehner says it's Democrats' turn for a Tea Party movement House Republicans find silver lining in minority Alaskan becomes longest serving Republican in House history MORE (R-Ohio) is expected to easily win his race on Tuesday against Tea Party challenger J.D. Winteregg (R), but has spent hundreds of thousands on television ads to make sure the race isn’t close. Winteregg has the backing of the Tea Party Leadership Fund, which has spent more than $300,000 on his behalf. But he’s drawn the biggest headlines for losing his job at a local Christian university after his Web ad accusing BoehnerJohn Andrew BoehnerBoehner says it's Democrats' turn for a Tea Party movement House Republicans find silver lining in minority Alaskan becomes longest serving Republican in House history MORE of “electile dysfunction” went viral.

Freshman Rep. David Joyce (R-Ohio) also faces a Tea Party test from Ohio state Rep. Matthew Lynch (R). Joyce has benefitted in hundreds of thousands spent from the U.S. Chamber of Commerce and the Defending Main Street super-PAC, a group run by former Rep. Steve LaTourette (R-Ohio), Joyce’s predecessor in the district.

Lynch has the backing of former Rep. Ron Paul (R-Texas), FreedomWorks and the Tea Party Patriots. Analysts believe Joyce has the edge in the race, though if Lynch pulls off the upset the swing district could be in play this fall.

A pair of Democratic primaries in North Carolina are worth watching as well.

Former “American Idol” runner-up Clay Aiken (D) is vying for the right to face Rep. Renee Ellmers (R-N.C.) in a heavily Republican district. North Carolina Democrats say Aiken has run a strong race, but self-funding businessman and former North Carolina Commerce Secretary Keith Crisco (D) has outspent him on the airwaves and may have the edge in the race. Either Democrat would still face an uphill fight in the conservative district against Ellmers this fall. 

A crowded Democratic field in the special election primary to succeed former Rep. Mel Watt (D-N.C.), who left in January for a job in the Obama administration, will be slimmed to two candidates as well. North Carolina state Rep. Alma Adams (D), who’s had the support of EMILY’s List, looks likely to make the runoff. North Carolina Democrats say state Sen. Malcolm Graham (D) and attorney George Battle (D) are the two most likely to emerge against her on Tuesday.

Indiana is also holding its primary Tuesday, though few think there will be close results in any of the state’s federal races.

Polls in North Carolina and Ohio close at 7:30 p.m. while all Indiana polls will close by 7 p.m. EDT.