The nominees have been accused of using their debate invitations to get under their opponent's skin — and appear to be trying to outdo each other with their potential guests. 
 
ADVERTISEMENT
Billionaire Mark Cuban, an outspoken critic of Donald Trump, last week announced he had accepted an invitation from Clinton's campaign to sit front-row at the debate on Monday night.
 
In response, Trump threatened to bring Gennifer Flowers, a woman with whom Clinton's husband, former President Bill ClintonWilliam (Bill) Jefferson ClintonTrump’s first year in office was the year of the woman Can a president be impeached for non-criminal conduct? Dems search for winning playbook MORE, had an extramarital affair.
 
The GOP nominee tweeted Saturday if "dopey Mark Cuban of failed Benefactor fame wants to sit in the front row, perhaps I will put Gennifer Flowers right alongside him."
  
Flowers later appeared to accept the invitation: "Hi Donald. You know I'm in your corner and will definitely be at the debate," she tweeted in response.
 
Bill Clinton testified under oath in 1998, saying he had an affair with Flowers.
 
But members of Trump's campaign on Sunday denied that Flowers was officially invited and said she will not attend.
 
Republican vice presidential nominee Mike PenceMichael (Mike) Richard PenceThe House needs to help patients from being victimized by antiquated technology 'The Wire' star: I'd prefer a President Pence because he's a 'simpleton and a puppet' Trump looks to steer UN effort on Afghanistan, with McMaster and Haley at the helm MORE confirmed Flowers wouldn't be at the debate and said his running mate's tweet was meant to mock Clinton for "trying to distract attention away from this moment in our national life where the American people are going to see a strong contrast" between both major party's nominees.
 
Pence criticized the Democratic nominee for extending an invitation to Cuban.
 
"Hillary Clinton apparently thinks this is an episode of 'Shark Tank,' but this is America," Pence said on "Fox News Sunday," referring to the ABC show Cuban has appeared on as an investor. 
 
"It's serious business."
 
Trump's campaign manager, Kellyanne Conway, echoed Pence's comments, saying Flowers isn't expected to be at the presidential debate as Trump's guest.
 
"Mr. Trump was putting them on notice that we could certainly invite guests that make it into the head of Hillary Clinton," Conway said Sunday morning.
 
Debate commission co-chairman Frank Fahrenkopf warned both nominees against using their invites to try to disrupt the debate.
 
"We're going to frown upon — I will tell you this right now — whether or not a Republican or Democrat or anyone else attempts by use of the tickets in placing people in a front-row or not to try to impact the debate," he said Saturday on CNN.
 
"It's wrong. We would frown upon Mr. Cuban being in the front row if his purpose is to somehow disrupt the debate. Likewise, if Mr. Trump was going to put someone in the front row to try to impact things."
 
Still, Fahrenkopf said the debate commission has been working with the both campaigns' staff and doesn't expect any problems.
 
"They're approaching this in a very dignified manner — the way I think it should be approached," he said.
 
On Sunday, members of Clinton's campaign defended the decision to invite Cuban to the debate, touting his accomplishments and denying it's an attempt to annoy Trump.
 
Clinton's chief strategist, Joel Benenson, called Cuban a "successful businessman" whose economic beliefs often match Clinton's.
 
"I think it's legitimate to have a businessperson sitting there who's been advocating for you because of your economic policies," Benenson said on "Fox News Sunday."
 
Benenson noted that Cuban believes in things such as profit-sharing to help increase wages. He pointed to the many businesspeople who have endorsed the Democratic nominee and touted her plans to grow the economy and help get incomes rising for working Americans. 
 
"As opposed to a candidate like Donald Trump, who says he thinks wages are too high in America and we should get rid of the federal minimum wage," Benenson added.
 
Cuban has criticized Trump several times during the GOP nominee's campaign, often taking jabs at the candidate on Twitter. Cuban has questioned Trump's wealth, called for him to release his tax returns and slammed him for his lack of transparency.
 
When Cuban announced in July he would vote for Clinton, the billionaire said he'd do his best to convince everyone he knew to do the same.
 
Earlier this month, Cuban offered Trump $10 million for an interview about policy proposals.
 
Still, aides to both Trump and Clinton are saying their candidate plans to focus on the issues facing the country when they come face-to-face on Monday.
 
Benenson said on Sunday that the event is for the American people. Voters want to hear a substantive debate between Clinton and Trump so they can decide which candidate has the "experience, knowledge and judgment to implement plans that will make a real difference in their lives," he said.

"That's what Hillary Clinton's going to be focusing on," he said.

"Talking to the American people about their lives, what she's going to do for them, how she's going to get things done, that'll help them get ahead."

 Conway, Trump's campaign manager, praised the GOP nominee's debate skills, calling him a "brilliant debater."
 
"He's like the Babe Ruth of debating. He really shows up and swings and does a great job," she said Sunday on ABC's "This Week."
 
Monday's debate, moderated by "NBC Nightly News" host Lester Holt, is expected to be the most watched ever, with an audience that could exceed 100 million people.
 
An audience of that size would be something never seen before in U.S. politics.