Today is a big day in the Republican primary for Pennsylvania governor.

Or maybe not.

Ever since former President Donald Trump announced he would be holding a rally in Western Pennsylvania on May 6, the candidates have had the date circled on their calendars.

The rally Friday is meant to boost Mehmet Oz, the celebrity doctor and Trump’s pick in Pennsylvania’s U.S. Senate race. But GOP insiders are wondering whether Trump — who has a penchant for theatrics — will also use the occasion to make an endorsement in the nine-candidate gubernatorial primary.

He could come out in favor of the front-runner, State Sen. Doug Mastriano, and perhaps seal the nomination for him. Or he could pick another candidate, most likely one of the other leading contenders, former U.S. Rep. Lou Barletta or former Delaware County Councilman Dave White. Barletta and White — along with state Senate leader Jake Corman, who has trailed the top candidates — are expected to attend, aides say. Mastriano is said to have been invited, though his plans weren’t immediately clear.

The only thing that appears certain: Trump won’t be supporting Bill McSwain, the former U.S. attorney in Philadelphia who Trump called a “coward” last month for not prosecuting baseless claims of voter fraud in 2020.

» READ MORE: From April: Trump is sowing chaos in the Pennsylvania governor’s race

It has all the trappings of a Trumpian made-for-TV moment. In a crowded race with a large share of undecided voters, Trump’s decision could be decisive.

Or it could amount to nothing.

“Tense,” Val Biancaniello, a Delaware County Republican activist, said of the mood ahead of Friday’s rally. “No one knows if he’s going to endorse. Trump is known to be somewhat impulsive. It’s a close race.”

The candidate she’s backing, White, said he scored “VIP tickets” to the rally. But White — who met with Trump at his Mar-a-Lago resort in Florida last week — offered no prediction about an endorsement. “I will be at the rally listening to the president speak, and I’m looking forward to it,” White said in an interview Thursday evening during a campaign event in Drexel Hill.

Barletta said he’s also going. Does he expect Trump to say something nice about him? “He usually does a nice shout out,” Barletta said in an interview Wednesday in South Philadelphia.

He said Trump’s word could make the difference in the race. “Look at Ohio,” Barletta said, referring to Trump-backed J.D. Vance’s victory in the GOP Senate primary there this week. “It carries a lot of weight.”

Corman is trying to stay in the mix, too. Although he has trailed in the polls, Corman appears to have struck up a rapport with Trump over golf. And the senator posted pictures of himself with his daughter at Mar-a-Lago on Thursday, where they attended a screening of an election conspiracy film called 2000 Mules. “It’s a movie every American should see,” Corman said on Twitter.

Corman was accompanied by campaign adviser Kellyanne Conway, the former Trump aide who’s also featured in Corman’s TV ads.

Even McSwain projected confidence ahead of the rally — not about his prospects for an endorsement, but on his path to victory. McSwain is far out-spending his rivals on television ads — helping him stay afloat despite Trump’s anti-endorsement.

“People need to recognize that my campaign is the only campaign over the last several months that has been consistently going up,” McSwain said in an interview Wednesday in Philadelphia, as he promoted his plan to cut the state gas tax by 50%. “And momentum is key. And we want to peak on election day. The other campaigns are either flat or have been drifting downward. … We feel really good about where we are. The plan has always been to peak on May 17.”