Former Ohio Gov. John Kasich -- one of President Trump’s most vocal Republican critics -- was asked to participate in the Democratic National Convention “because of his opposition” to Trump, former White House press secretary Ari Fleischer told “Outnumbered Overtime” on Tuesday.

He added that Kasich’s participation is “also illustrative of a party that’s changing.”

“The Republican Party is increasingly becoming a blue-collar, working-class party and the Democrats are increasingly becoming a college-educated party,” Fleischer, a Fox News contributor, said. “We’ve seen this in the suburbs, we’ve seen this with traditional establishment Republicans who have left the party because of distaste for Donald Trump, while the Democrats are hemorrhaging blue-collar working class people.”

“Both parties are kind of moving in opposite ways of what they used to represent and I attribute that to John Kasich as a piece of that with the added element that he can’t stand Donald Trump,” he continued.

Kasich took aim at President Trump during a speech on the first night of the DNC and urged other Republicans to join him in voting for the Democratic ticket in November.

Kasich — a Trump rival during the 2016 GOP presidential primaries who never endosed his party's eventual nominee — on Monday offered his support to presumptive Democratic presidential nominee Joe Biden and called on fellow Republicans "to take off our partisan hats and put our nation first for ourselves and of course for our children."

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Criticizing the president, Kasich argued that "many of us have been deeply concerned about the current path we’ve been following for the past four years. It’s a path that’s led to division, dysfunction, irresponsibility and growing vitriol between our citizens. Continuing to follow that path will have terrible consequences for America’s soul because we’re being taken down the wrong road by a president who has pitted one against the other."

Host Harris Faulkner asked Fleisher on Tuesday, “Who is the audience there?”

“The audience is college-educated Republicans who question whether they should stay Republicans. That’s who Kasich is talking to,” Fleisher said in response.

He went on to explain that “the question immediately comes down to math: Are there more blue-collar workers who voted for Obama in 2008 and 2012 than voted for Donald Trump in 2016 and will do so in even greater numbers in 2020 than there are suburban college-educated Republicans who are leaving the Republican Party?”

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“That’s what this comes down to and that’s why Donald Trump’s job is to rev up that number of blue-collar high school educated, less than college-educated voters who increasingly just don’t see the Democratic Party, particularly with their move toward the left, toward socialism, representing them anymore,” Fleisher continued. “Both parties are going through fluid, dynamic changes and elections capture that.”

Fox News’ Paul Steinhauser contributed to this report.