On ABC, Trump pointedly refused to comply with Republican National Committee Chairman Reince Priebus' call for Republican presidential candidates to pledge not to run third-party campaigns if they do not get the nomination.
At the moment, Trump is hopeful he can moot the question: Polls continue to show him leading the race for the Republican presidential nomination. The most recent is a Wall Street Journal poll, which will be released in full on Monday.
In a preview of the results posted Sunday, the Journal said Trump is the top choice of 19 percent of primary voters, with Scott Walker coming in second place with 15 percent.
Trump's poll performance has made him a lock for Thursday's prime-time Republican primary debate, hosted by Fox and Facebook.
In another Sunday appearance on CBS' Face the Nation,Trump opined on the Democratic presidential race, discussing reports that Vice President Joe Biden may be considering a challenge to front-runner Hillary Clinton.
"I think that Biden would have a good chance at beating her now," Trump said.
"I don't think he could've beaten her six months ago, or even three months ago. I think the e-mail scandal is going to be a devastating blow for Hillary, if you have an honorable prosecutor, which we'll see whether or not that happens, because they're all Democrats."
The reference was to Clinton's decision to use a private e-mail account and server when she was secretary of state, which has raised questions about the security of her e-mails and the integrity of the historical archive.
Asked about whether he will release his own tax returns, as a number of other presidential contenders, including Clinton, already have done, Trump took the opportunity to tweak the Democrat again.
"I have no major problem with it," he said. "But I may tie them to a release of Hillary's emails."
Trump did not say what percentage of his income he pays in taxes, and was open about the efforts he makes to keep his rates low.
"I fight like hell to pay as little as possible for two reasons," Trump said. "Number one, I'm a businessman. And that's the way you're supposed to do it. And you put the money back into your company and employees and all of that. But the other reason is that I hate the way our government spends our taxes. I hate the way they waste our money. Trillions and trillions of dollars of waste and abuse. And I hate it."