The contest to become former President Donald Trump's vice presidential pick heated up Wednesday, after the Trump campaign reportedly sent out vetting requests to key candidates.

The vetting packages, reported by The Hill and ABC News, come just over a month before the Republican National Convention, where Trump is expected to receive the party's nomination alongside his vice presidential candidate. The packages were sent to seven possible choices, including Trump's former competitor South Carolina Sen. Tim Scott.

The four top contenders for the nomination are Scott, Florida Sen. Marco Rubio, North Dakota Gov. Doug Burgum who also launched a longshot bid for the GOP nomination, and Ohio Sen. J.D. Vance. The four appeared with Trump recently after he was convicted of falsifying his business records to hide a hush money payment to former porn star Stormy Daniels. But Ben Carson and Reps. Byron Donalds and Elise Stefanik have also received the vetting materials, according to ABC News.

Trump has teased that he could reveal his running mate at the Republican convention, which will take place in Milwaukee, Wisconsin from July 15-18. The former president has praised the four frontrunners recently, telling Newsmax that all of them have been great when it comes to campaigning for him.

“I thought Tim Scott didn’t run as good of a race as he’s capable of running for himself, but as a surrogate for me, he’s unbelievable. He’s been incredible,” Trump said. “Gov. Burgum from North Dakota has been incredible. Marco Rubio has been great. J.D. Vance has been great. We’ve had so many great people out there.”

Although Rubio is considered a top tier choice for VP, he has denied hearing from the Trump campaign about being vice president, or receiving a request for vetting documents. But Rubio, along with Burgum and Vance, said he would do whatever Trump's campaign asked of him.