The roster of House Democrats planning to boycott President-elect Donald Trump's inauguration grew to about 50 on Tuesday in a protest of the New York businessman's policies and his repeated criticism of legendary civil rights activist John Lewis.

The Georgia congressman made headlines over the weekend for challenging Trump's legitimacy to be the next president and erroneously claiming that Trump's inauguration would be the first he will have missed since coming to Congress three decades ago.

In fact, Lewis had skipped President George W. Bush's inauguration in 2001.

Trump struck on Tuesday morning, as is typical, on Twitter: "WRONG (or lie)!" Trump tweeted, citing a 2001 Washington Post report that noted Lewis had skipped George W. Bush's inauguration.

Lewis' office on Tuesday confirmed that the congressman had missed Bush's swearing-in.

"His absence at that time was also a form of dissent," said spokeswoman Brenda Jones. "He did not believe the outcome of that election, including the controversies around the results in Florida and the unprecedented intervention of the US Supreme Court, reflected a free, fair and open democratic process."

Lewis said last week that he would skip Trump's swearing in on Friday, telling NBC News that he didn't view Trump as a legitimate president.

"I think the Russians participated in helping this man get elected. And they helped destroy the candidacy of Hillary Clinton," Lewis said in an interview with NBC's Meet the Press.

Lewis' comments drew angry weekend tweets from Trump, who wrote that "rather than falsely complaining about the election results," Lewis should focus on his congressional district.

House Speaker Paul Ryan, also weighed in, telling Fox television on Tuesday that Trump "won this election fair and square" and that Democrats were wrong "to try and inject some kind of claim of illegitimacy on the dawn of a new presidency".

Ryan praised Lewis, however, telling Fox6Now.com that Lewis "knows what I think of him, how much I look up to him. I think both men would do better by just getting to know each other, and understanding each other."

The number of Democrats boycotting Trump's inauguration continued to increase, including Minnesota Rep. Keith Ellison, a top contender to lead the Democratic National Committee, as well as many black and Hispanic lawmakers. Top Democrats like House Minority leader Nancy Pelosi and Senate Democratic leader Chuck Schumer of New York will attend, however, and none of the Senate Democrats said they'll skip the inauguration.

Trump spokesman Sean Spicer shrugged off the protest and indicated they would give away the seats.

"We'd love for every member of Congress to attend but if they don't, we've got some great seats for others to partake in. It's a shame that these folks don't want to be part of the peaceful transfer of power," Spicer told reporters.