Trump-endorsed Vance projected winner in Ohio

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.

Voters head to the polls in Ohio on Tuesday on the heels of a shocking leak of a Supreme Court draft opinion suggesting the court's conservative majority may overturn nearly 50 years of abortion rights in America.

The endorsement power of former President Donald Trump -- who promised to appoint Supreme Court justices who would overturn Roe -- faces a major test in the race of retiring Republican Sen. Rob Portman in Ohio. While almost all the GOP candidates have centered their campaigns around being a Trump conservative, "never-Trumper" turned Trump ally J.D. Vance scored his coveted endorsement, upending the race.

On the Democratic side, the contest in Ohio's 11th Congressional District between Rep. Shontel Brown and Nina Turner has pitted establishment Democrats against progressives. Biden endorsed Brown over Turner last week in his second primary endorsement of the election cycle, but progressives including Vermont Sen. Bernie Sanders have backed Turner.

A new ABC News/Washington Post polling out Tuesday shows that 60% of Republicans and GOP-leaning independents want the GOP to follow Trump’s leadership -- about where that’s been since he left office. By contrast, only about 53% of Democrats and independents who lean that way want to follow Biden’s leadership, with younger Democrats most solidly favoring a new direction.

-ABC News' Political Director Rick Klein