Trump-endorsed Vance projected winner in Ohio

In the final hours of Ohio's Senate primary, Republican candidates were quick to praise the prospect of overturning Roe v. Wade as the stunning leak of a Supreme Court draft opinion rocked the race overnight.

"I do think Roe was a big mistake. And I think if the Supreme Court overturns it, it will be a big success for the pro-life movement," J.D. Vance, who got former President Donald Trump's endorsement, told ABC News Congressional Correspondent Rachel Scott.

"If it gets overturned, we're gonna have a fight here in the state of Ohio. And I think I'm going to be on the front lines of that fight trying to get us here in Ohio to protect it," he added.

Rep. Tim Ryan -- the Democrats' likely candidate in the hotly contested race, who once opposed abortion rights but changed positions in 2015 -- called it a "freedom issue" that he predicted would motivate a lot of women "to vote for a senator who would be on their side."

"I think in many ways to abortion is, in some sense, an economic issue as well. Should a woman be able to plan the size of her family? Should a woman be able to plan when she has a pregnancy? This is a freedom issue, really, for me, and I think it's a freedom issue for a lot of these women," Ryan told ABC News Senior Washington Reporter Devin Dwyer.

Ohio and Indiana are among the 26 states which are likely or certain to ban abortion if Roe falls or is gutted, according to the Guttmacher Institute, an abortion rights research organization.

Tuesday's rematch between Rep. Shontel Brown and former state senator Nina Turner for Ohio's 11th Congressional District offers a real-time reflection of the divisions between the Democratic Party's progressive and establishment wings -- and a barometer for Democrats running across the country at the top of the midterm season.

Brown was first elected to Congress in a special election last year following former Rep. Marcia Fudge's appointment to serve as secretary of the Department of Housing and Urban Development. While President Joe Biden endorsed Brown last Friday, calling her "an ardent advocate for the people of Ohio and a true partner in Congress,” leading progressive voices like Sen. Bernie Sanders of Vermont and Rep. Alexandria Ocasio-Cortez, D-N.Y., are backing Turner.

Turner and Brown approached the campaign trail from different ends of the Democratic political spectrum. Turner, a former co-chairwoman of Sanders' 2020 presidential campaign, has previously criticized the Democratic Party and Biden.

Tuesday's Ohio Senate primary is among the first litmus tests of many this midterm season to gauge how much influence former President Donald Trump holds over the Republican Party. Almost all of the candidates -- except for Matt Dolan -- align with the former president, so even if "Hillbilly Elegy" author J.D. Vance doesn’t win, the GOP nominee could well be a Trump-aligned Republican who endorses falsehoods about the 2020 election.

Another race seen as a test of Trump's kingmaking power is in Ohio's 7th Congressional District, where the former president endorsed challenger and former aide Max Miller.

President Joe Biden, meanwhile, chose to hand out only his second primary endorsement of the cycle in Ohio to Rep. Shontel Brown in her rematch against progressive powerhouse Nina Turner, a close ally of Sen. Bernie Sanders, in a race that has pit establishment Democrats against progressives.

Gov. Mike DeWine, who is seeking a second term, is expected to survive a Trump-inspired, though not endorsed, challenge to his COVID governance and establishment leanings.

-ABC News' Political Director Rick Klein

Some races in Indiana -- such as the state's 1st Congressional District where a slew of Republican challengers are vying to win the seat held by incumbent Democratic Rep. Frank Mrvan -- are seen as possible bellwethers for whether Republicans manage can flip districts in Democratic strongholds.

Indiana’s 9th Congressional District -- the only vacant congressional seat in the state -- is also in play when it comes to which party will control the House of Representatives after the midterms.

Along with Ohio, the state is an early indicator of the power of former President Donald Trump’s endorsement, as Trump carried the state in 2020. Trump has backed six incumbent members of the House of Representatives in the state, including Rep. Greg Pence, former Vice President Mike Pence’s brother.

Polls close in Indiana at 7 p.m. ET, though there is some variation because the state falls within two time zones.