Late night comedians had a lot of fun at Mitt Romney’s expense after the 2012 Republican presidential candidate gave a speech attacking current Republican front-runner Donald Trump. On Tuesday, Romney cut out the middle man and appeared on “Jimmy Kimmel Live” to continue his crusade against Trump and address rumors of his own candidacy.

Host Jimmy Kimmel asked Romney about his “perfect hair,” Bernie Sanders, and, of course, Donald Trump. The comedian had Romney read “mean tweets” about himself from Trump — Kimmel has a regular segment where celebrities read mean tweets about themselves — before asking him why he opposes the current Republican front-runner. 

“For me, the straw that broke the camel's back was [Trump] not denouncing David Duke,” Romney said. "The great majority of Republicans want someone other than Donald Trump to be the nominee and I want to help that person become President."

Watch Mitt Romney discussing Donald Trump on "Jimmy Kimmel Live!" in the clip below:

Despite Romney's efforts to stop Trump, the businessman seems destined to be the Republican nominee. Kimmel asked Romney what he would do if he was forced to vote for either Trump or presumed Democratic nominee Hillary Clinton. 

"I would either write in a name on the ballot or I would find some other candidate in there who was a conservative who I could support," said Romney, later joking that he would write in Kimmel's name. 

Would Romney run himself? Some Republicans, including Romney, have been advocating for a brokered convention, in which Republican delegates could choose a candidate other than Trump and the candidates currently in the GOP field. Rumors have been swirling that Romney could be the candidate to emerge as the nominee in that scenario. 

"No, no, no. There are four people running for president [in the GOP]," said Romney. "One of them will be our nominee."

Watch Mitt Romney address rumors of his own candidacy in the clip from "Jimmy Kimmel Live!" below:

On March 3, Romney gave a speech at the University of Utah in Salt Lake City, denouncing Donald Trump and laying out a plan to halt his path to the Republican nomination. 

"His is not the temperament of a stable, thoughtful leader," Romney said in his speech, calling Trump "a phony" who is "playing the American public for suckers."

However, Romney's speech — and the efforts of many other establishment Republicans — have failed to stop Trump's momentum thus far. On Tuesday, Trump picked up wins in three more primaries (Michigan, Mississippi and Hawaii), extending his already-significant lead in the delegate count. Trump now has 458 delegates. Texas Sen. Ted Cruz is a distant second with 359 delegates, followed by Florida Sen. Marco Rubio with 151 delegates and Ohio Gov. John Kasich with 54 delegates. 1,237 delegates are needed to secure the nomination and avoid a brokered convention. 

Watch Mitt Romney read mean tweets from Donald Trump in the clip from "Jimmy Kimmel Live!" below: