The race to become Donald Trump's running mate is heating up, as the presumptive Republican nominee has been huddling with top contenders. But the expected announcement is competiting for attention, as word is surfacing Trump is engaged in a bitter legal fight with a former top aide. Josh Robin filed the following report.

Mike Pence, the Indiana governor, is seen as a top candidate to be Donald Trump's right-hand man. Trump even flew out his family to meet him.

"I truly do believe that Donald Trump has the right vision for America," Pence said. "He's going to provide the kind of strong leadership at home and abroad that's going to make America great again."

Trump also appeared with Pence Tuesday night, playing coy.

"You'll be calling up Mike Pence, I don't know whether he's going to be your governor or your vice president," Trump said.

Last week, it was Newt Gingrich on audition. And other names include New Jersey Governor Chris Christie, Alabama Senator Jeff Sessions and Michael Flynn, former head of the Defense Intelligence Agency.

Meanwhile, Trump, who has known to sue amid disagreements, is now in a legal battle with a former top aide. He accuses Sam Nunberg of leaking confidential information about an alleged affair between Trump's spokeswoman and former campaign manager, according to Nunberg's attorney.

Nunberg's attorney adds his client didn't violate a non-disclosure agreement and is being targeted for supporting another candidate.

Trump's campaign didn't return an email.

Meanwhile, Hillary Clinton traveled to Abraham Lincoln's old haunts to warn of Trump's effect on the Republic.

"This man is the nominee of the Party of Lincoln. We are watching it become the Party of Trump. And that's not just a huge loss for our democracy. It is a threat to it," Clinton said. "His campaign is as divisive as any we've seen in our lifetimes. It is built on stoking mistrust and pitting American against American."

Trump is again criticizing Clinton on Twitter, calling her crooked.