Republican voters trust Donald Trump as the candidate most likely to defeat Joe Biden, a Monmouth University survey found.

The poll undercuts the argument from Trump's Republican rivals, Ron DeSantis particularly, that the former president cannot win the next presidential election.

63 percent of Republican voters said Trump has the best chance of defeating Biden, while roughly a third of Republican voters say another candidate would handle the job better.

Poll: Trump electable

Nearly half (45 percent) say Trump is "definitely" the strongest candidate, and 18 percent say "probably."

To hear some tell it, Trump is virtually guaranteed to hand the Democrats four more years in the White House. But that's not what the voters think.

"If your message to voters who support Trump is he cannot win, you are going to hit a brick wall. Even if you eat into the group who thinks he is only ‘probably’ the strongest candidate, you may still not capture enough of the Republican electorate to overcome Trump’s hardcore base support," pollster Patrick Murray said.

Long seen as the biggest threat to Trump from within the GOP, DeSantis launched his candidacy last week after months of anticipation that saw the governor's momentum slowly ebb.

The Monmouth Poll found the governor down 20 points since December, when he was riding high off a re-election landslide. DeSantis is now backed by just 19 percent of Republican voters, while Trump's lead has grown to 43 percent.

DeSantis stumbles out the gate

Trump is also leading DeSantis in a head-to-head 56-35 percent. For contrast, DeSantis was leading Trump 53-40 in February. Trump is now leading with all major GOP demographics polled except college graduates.

It's worth noting that the poll was conducted before DeSantis' campaign launch. It remains to be seen if DeSantis can right the ship, but he is entering the race on weaker footing than many expected.

“DeSantis lost ground even before he got out of the starting gate. Republican voters still like him, but they haven’t heard a convincing case for why he would be the party’s best option,” Murray said.

In terms of favorability, Republicans rank Trump and DeSantis about the same: 77 percent have a positive view of Trump versus 74 percent for DeSantis.

The poll was conducted from May 18 to 24, with 655 Republican and Republican leaning voters and a margin of error of 5 percentage points.

DeSantis told donors recently that he is the only Republican who can beat Biden, but the governor's apparent stumbles appear to have emboldened rivals like former vice president Mike Pence, who is reportedly entering the race next week.