Republican Sens. Marco Rubio and Pat Toomey became the latest Republicans to speak out against Donald Trump's warnings of a rigged election Monday night.

In separate high-stakes debates, the two incumbent U.S. senators each refuted Trump's claim that the results of the 2016 election could be tainted, and both men called for confidence in next month's vote.

"Our elections may not always be completely perfect, but they are legitimate, they have integrity and everyone needs to respect the outcome," Toomey said during his debate with challenger Katie McGinty when asked about the Republican presidential nominee's allegations, which he's been repeating on the stump all week.

Toomey said that the success of the American "republic" depends on citizens' "confidence in the outcome of the elections" and said voters should respect the outcome, "because that's going to be necessary to pull us all together on Nov. 9."

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Rubio, in his debate with Democratic Rep. Patrick Murphy, said the election is "absolutely" not being rigged and "I hope [Trump] stops saying that."

Rubio offered a more extensive rebuttal to Trump's claims. Visibly irritated, he noted that Florida's 67 counties all conduct their own elections. "I promise you there is not a 67-county conspiracy to rig this election," he said, adding that Florida Gov. Rick Scott is a Republican and appoints those who run the elections.

"Third, there's no evidence behind any of this and so this should not continue to be said," Rubio added.

Rubio also cited the "millions of people who came [to Florida] because they couldn't vote in the nation of their birth," a reference to the state's sizable Cuban population. "It would be a tragedy if they gave up their vote here as well."

Toomey and Rubio's respective Democratic opponents attacked the senators for not opposing Trump. Murphy called Trump "unhinged," and McGinty said his election skepticism is a "dangerous, reckless allegation."

Rubio has endorsed Trump and maintained his support Monday night; Toomey has yet to endorse Trump but has left the door open to voting for him.

Trump has increased his warnings in recent days, saying without citing evidence that voter fraud is "very, very common," asserting that undocumented immigrants and "people that have died 10 years ago" vote.

Some election observers have expressed concern that his focus on the prospect of a tainted election could spark a revolt among his supporters if he loses.

Even Trump's running mate, Indiana Gov. Mike Pence, sought to walk Trump's rhetoric back over the weekend, telling "Meet the Press" that he and Trump "will absolutely accept the results of the election."

"One of the great, great traditions of America is the peaceful transfer of power," Pence said. "Elections get rough. I expect they're going to stay just as rough as they are right now going into Nov. 8. The stakes are so high in this election."