LOUISVILLE, Ky. — Sen. Tim Kaine endured being denied the vice presidency despite running on a ticket that won the national popular vote. But the Virginia Democrat on Monday downplayed the prospects for doing away with the Electoral College, which sealed Republican Donald Trump’s election to the White House.

Kaine said abolishing the Electoral College would require a change to the U.S. Constitution – with the “really onerous requirement” of being ratified by an overwhelming majority of states.

“It’s not going to happen because smaller states really like the Electoral College,” Kaine told an audience at the University of Louisville.

The idea has gained traction among Democrats since Hillary Clinton lost the 2016 presidential election. She netted nearly 3 million more votes than Trump, yet lost the Electoral College and therefore the White House to him. Kaine was Clinton’s running mate.

Some candidates in the crowded race for next year’s Democratic presidential nomination have already jumped aboard the push to scrap the Electoral College, tapping into Democratic anger over the election process. Trump became the second Republican in five elections to win the presidency through the Electoral College while losing the popular vote.

The Electoral College, a group that comes together every four years to technically elect the president, is enshrined in the Constitution.

“You might do it differently if you were starting from scratch,” Kaine told the campus audience. “But it’s not going to get the support of this overwhelming majority of states. So I tend to focus on the things that I think I can really make a difference on. And I think that’s not that productive a use of a whole lot of energy.”

Meanwhile, several Democratic-controlled states are pushing for a national popular vote. But rather than pass a constitutional amendment, those legislatures are joining the National Popular Vote Interstate Compact, a group of states that pledge to give their electoral votes to the winner of the national popular vote.

The compact would only go into effect when it includes states representing 270 electoral votes, the majority needed to win the White House.

Kaine, a former mayor and governor, delved briefly into the sting of losing the 2016 election.

“I had never lost a race. I can’t say that anymore. I can say I’ve never lost a popular vote on any ballot that I’ve been on,” he said, drawing applause from the audience. “And I’ve never lost the Virginia vote.”

Kaine recalled that his first visitor after he returned to the Senate following the 2016 loss was Republican John McCain, who lost to Democrat Barack Obama in the 2008 presidential election.

“He said, ‘Tim, I’m the only person here who knows exactly how you feel,'” Kaine recalled. “‘You and me are the only two that have been on a national ticket and lost. … And I’m just here to tell you, that the answer to what you’re feeling is just go right back to work.’ And I said, ‘You found me here, didn’t you?'”

On another issue, Kaine said he’s confident that special counsel Robert Mueller’s full report on the Russia investigation will eventually reach the public “because you can’t keep a secret in Washington.” Attorney General William Barr released a four-page summary that detailed Mueller’s “principal conclusions” and says a redacted version will be sent to Congress.

Asked about impeachment talk among some Democrats against Trump and how Congress should respond, Kaine replied, “You should not jump to a conclusion about something so momentous and weighty before all the facts are out on the table.”

Kaine spoke as part of the McConnell Center Distinguished Speaker Series at UofL. He was introduced by Senate Majority Leader Mitch McConnell, a Kentucky Republican and a UofL graduate.