Just 4 in 10 Republicans say they think President TrumpDonald John TrumpKamala Harris calls for Twitter to suspend Trump account over whistleblower attacks Clinton jokes she 'never' had to tell Obama not to 'extort foreign countries' John Dean: 'There is enough evidence' to impeach Trump MORE discussed an investigation into Democratic presidential rival Joe BidenJoe BidenKamala Harris calls for Twitter to suspend Trump account over whistleblower attacks Clinton jokes she 'never' had to tell Obama not to 'extort foreign countries' John Dean: 'There is enough evidence' to impeach Trump MORE during a phone call with Ukraine's president, despite Trump acknowledging having done so, according to a new Monmouth University poll.

The survey, which was released Tuesday, found that 40 percent of Republican respondents said Trump "probably did" raise the idea of an investigation into Biden and Biden's son over unsubstantiated allegations of corruption during a July 25 conversation with Ukrainian President Volodymyr Zelensky. Meanwhile, 29 percent of Republicans said Trump "probably did not" mention an investigation into Biden.

That compares to 85 percent of Democrats and 61 percent of independents who said Trump likely raised the issue of an investigation into Biden during the call. In total, 62 percent of respondents said Trump likely raised the issue with the Ukrainian leader.

The Monmouth poll was conducted from Sept. 23 to Sept. 29, as the Ukraine story continued to unfold, with multiple reports emerging about Trump's interactions with the Ukrainian leader.

Trump on Sept. 22 acknowledged discussing Biden on the phone call, while a White House memo released three days later showed Trump pressing Zelensky to "look into" the Democratic candidate while repeatedly encouraging the Ukrainian leader to work with his personal attorney Rudy GiulianiRudy GiulianiOcasio-Cortez blasts McCarthy as a 'bumbling, sloppy, dishonest mess' over Trump defense House Intel Dem: Giuliani could be held in inherent contempt if he ignores subpoena Giuliani says he's received subpoena 'signed only by Democrat Chairs who have prejudged this case' MORE as well as Attorney General William BarrWilliam Pelham BarrOcasio-Cortez blasts McCarthy as a 'bumbling, sloppy, dishonest mess' over Trump defense Giuliani says he's received subpoena 'signed only by Democrat Chairs who have prejudged this case' DOJ says Trump contacted foreign countries to assist Barr's Russia inquiry MORE.

“At the very least, it is clear from the readout that Trump discussed investigating Biden during the call. Even though this information was released by the White House itself, more than one quarter of Republicans still say Trump probably didn’t make any mention of it. This seems to be another example of partisan tribalism at work in public opinion,” said Patrick Murray, director of the independent Monmouth University Polling Institute. 

The margin of of error for the poll is 2.9 percentage points. 

Trump's interactions with Zelensky have embroiled his administration in controversy and prompted a formal impeachment inquiry in the House.

Amid the scrutiny, Trump has repeatedly defended his conversations with Zelensky, describing their July phone call as "perfect" and claiming that a whistleblower complaint filed over the call is "fraudulent."

"As I learn more and more each day, I am coming to the conclusion that what is taking place is not an impeachment, it is a COUP," Trump asserted in a tweet Tuesday night.

A majority of Americans said they oppose Trump's effort to ask a foreign government to investigate a political rival, according to the Monmouth poll.

Sixty-three percent of respondents in the poll said it was not appropriate for a U.S. president to make such a request. Just 21 percent said it was appropriate.