A former speaker of the House said Thursday that the roughly 60 Democratic members of Congress who plan to boycott President-elect Donald Trump's inauguration should hang their heads in shame.

'If you're a member of Congress, if you work that hard to get to be a part of the system ... all they're doing is make themselves look small and silly,' Newt Gingrich told 'Fox & Friends' hosts.

And the onetime conservative revolutionary, who led the Republican Party to a House majority in 1994 after four decades of back-benching, warned Democrats that their partisan stand could backfire.

'I mean, their left loves them. But as we used to learn the hard way, you know, you can have your partisans love you for a long time and stay in the minority.'

Asked what the late President Ronald Reagan would think of the boycott, Gingrich shot back: 'That they're childish and silly.'

Newt Gingrich, a former Republican Speaker of the House, said Ronald Reagan would have considered Democrats who boycott an inauguration 'childish'

Gingrich said on 'Fox & Friends' that the boycotters were 'small and silly' and doomed to remain a minority if they keep pandering to their far left flank

A feud between Congressman and civil rights icon John Lewis and the president-elect has more and more Democrats saying they'll skip Friday's swearing-in

A few Democrats stayed home when Reagan took the oath of office in 1981, and they galvanized their energies later that night around a 'counter-inaugural ball' hosted by a Democratic senator from Colorado.

Gingrich framed the left's boycott this time around in terms of national unity.

'The inauguration's not about Republicans. It's not about Donald Trump,' he said. 'The inauguration's about America. Why would you abandon America?

'You're at a moment when the nation is transferring power peacefully, unlike – no other country has done this as long as we have. You have all of the sense of the national establishment coming together, despite an occasional idiot.'

But despite nearly one-third of the House Democratic caucus not showing up, Gingrich insisted Friday's ceremony will be infused with 'optimism.'

'I mean, it doesn't matter which team wins. We are a naturally optimistic country,' he said.

The former speaker, a onetime college history professor who was at one point touted as a potential cabinet secretary, praised the president-elect for having 'a very strong sense of who he is and what his mission in history is.'

'And he also has frankly a better sense of how to talk with the American people than any Republican since Reagan.'

Cory Booker, one of the Senate's two black Democrats, (left) says he will attend despite a dispute between Lewis (right) and Trump

Gingrich joked about attending an afternoon tea at the British Embassy, saying UK power-brokers don't understand Donald Trump any better than 'the rest of us'

Keith Ellison, left, a Minnesota Congressman and leading candidate for Democratic Party head, said Monday, 'I will not celebrate a man who preaches a politics of division and hate.' Jerrold Nadler, right, a New York lawmaker, said he agrees with Lewis that Trump's 'illegitimate'

Reflecting with the 'Fox & Friends' host about a tea they attended Wednesday night at the British Embassy, Gingrich agreed that UK expats inhabiting Washington's corridors of power haven't yet figured out how to relate to the billionaire who will move into the White House on Friday.

'None of us know what to make of Donald Trump. Why should the British be ahead of us?' he quipped.

Corey Lewandowski, a former Trump campaign manager who has since turned lobbyist, told the same Fox News Channel hosts on Thursday that he's disappointed in the boycott news.

'I think the American people are so tired of partisan government and gridlock,' he said.

'It's a shame that some of these congressmen want to make it about hyper-partisan politics and not what's right for the American people. Give him a chance!'

Boycotters are taking their energy from civil rights icon John Lewis, who first said he would stay away from the U.S. Capitol on Friday – incorrectly stating that he'd never missed an inauguration before.

The Washington Post's latest tally had 65 Democratic representatives saying they would participate in a boycott - that's more than one-third of their caucus's 194 members.

Outgoing President Barack Obama told reporters on Wednesday that he was staying above the fray.

'With respect to the inauguration, I am not going to comment on those issues,' Obama said. 'All I know is I'm going to be there. So is Michelle.'

Michigan Representative John Conyers invoked Vice President Joe Biden's unrelated statement that Trump needs to 'grow up' and said he would protest the inauguration with Lewis

New York Rep. Yvette Clarke (left) said Trump had 'insulted America' with his remarks about Lewis. Bonnie Watson Coleman (right) said she plans to hold an interfaith prayer vigil in Trenton, New Jersey on Friday instead

Democrats who serve in the Senate are not breaking with tradition, despite their differences with Trump.

Senator Joe Manchin said Sunday that Lewis' boycott of the ceremony, that typically features lawmakers and former presidents standing behind the new president as he takes the Oath of Office, is 'uncalled for.'

The West Virginia senator, who was added this term to Democratic leadership and was went to New York to meet with Trump, said on CBS' Face the Nation that the altercation between the Republican president-elect and Lewis, a Georgia congressman, is 'non-productive.'

Both of the Senate's black Democrats are attending.

Newly elected California Sen. Kamala Harris told the Los Angeles Times she was going. New Jersey Sen. Cory Booker, who's often talked about as a prospective rival to Trump in the next election, said Monday at a breakfast he will participate in the 'peaceful transition of power.'

At an event recognizing the late Martin Luther King Jr. on his birthday, a federal holiday, Booker said he would follow the outgoing president's lead, like most of his Senate colleagues.

Three other California members of Congress who won't attend include (L-R) Jared Huffman, Barbara Lee and Ted Lieu

Trump has clobbered Lewis, saying he should 'finally' focus on 'the burning and crime-infested inner cities' instead of whining about the result of the 2016 election

'I respect everybody's choice in this. My personal feeling is this is the peaceful transition of power,' he said, according to USA Today. 'Barack Obama will be up there, handing off the reins of our country and I feel ... it's important for us to be up there. This doesn't mean I agree with Donald Trump.'

The fight between Lewis, who said Trump will not be a 'legitimate' president, and the president-elect, who responded on Twitter with personal and professional insults, turned the three-day holiday weekend that honors national civil rights hero Martin Luther King Jr. into a brand new battleground.

Trump's jabs at Lewis, who marched on Washington with Dr. King and was brutally beaten by police in Selma, Alabama, was met with outrage by congressional Democrats, many of whom are saying they won't go to his inauguration.

Even Michelle Obama got involved in the fight, highlighting Lewis in a tweet celebrating King and the advancement of civil rights.

Lewis, a congressman since 1987, told NBC's Chuck Todd on Friday, 'I don’t see this president-elect as a legitimate president. I think the Russians participated in helping this man get elected. And they helped destroy the candidacy of Hillary Clinton.

'I don't plan to attend the inauguration. It will be the first one that I miss since I've been in Congress,' he added. 'You cannot be at home with something that you feel that is wrong, is not right.'

Trump fired back on Twitter Saturday in a message that said, 'Congressman John Lewis should spend more time on fixing and helping his district, which is in horrible shape and falling apart (not to mention crime infested) rather than falsely complaining about the election results.

'All talk, talk, talk - no action or results. Sad!'

He doubled down on the claims later. 'Congressman John Lewis should finally focus on the burning and crime infested inner-cities of the US. I can use all the help I can get!' he said.

Lewis became famous in the 1960s as a prominent civil rights campaigner who became the youngest of the Big Six - the others included Martin Luther King Jr.

He took part in mixed-race 'freedom rides' across America, to challenge laws that demanded segregated buses. He was beaten multiple times and arrested for doing so. He had also been beaten multiple times by the KKK and others for participating in civil rights marches.

Trump struck out at 'angry' Democrats on Twitter Sunday, in what appeared to be a reference to the increasing numbers of representatives from the opposing party dropping out.

'The Democrats are most angry that so many Obama Democrats voted for me,' he said in a two-tweet tirade.

'With all of the jobs I am bringing back to our Nation, that number will only get higher. Car companies and others, if they want to do business in our country, have to start making things here again. WIN!'