Doug Lamborn gives a thumbs-up as President Donald Trump speaks during a campaign rally at the World Arena in Colorado Springs Thursday, February 20, 2020. (Mark Reis, Special to The Colorado Sun)

By James Anderson, The Associated Press

U.S. Rep. Doug Lamborn on Monday became the second member of Congress from Colorado to join an effort against certifying the Electoral College victory of President-elect Joe Biden.

Lamborn joined the state’s newest member of the House, Republican Lauren Boebert, in opposing certification, a move that deepened the rift in the state’s Republican delegation.

U.S. Rep. Ken Buck, outgoing chair of the state GOP, said Sunday that he won’t join dissident Republicans in challenging key states’ Electoral College votes. He said the Constitution doesn’t give Congress the authority to do so.

Congress is set to meet in a joint session Wednesday intended to take the final step in certifying Biden’s win following numerous failed court challenges by President Donald Trump’s campaign seeking to undo vote tallies in key states. Biden is set to be inaugurated Jan. 20.

Trump has enlisted support from at least a dozen Republican senators and roughly 100 House Republicans to challenge the vote when Congress considers Biden’s 306-232 win in the Electoral College.

Accepting the Electoral College vote is typically a routine process. But Trump refuses to concede.

Lamborn, serving his eighth term representing conservative El Paso County’s 5th Congressional District, cited what he called “serious irregularities and improprieties marring the 2020 election.” He said he’ll object to certifying Electoral College votes of Arizona, Georgia, Pennsylvania, Wisconsin, Nevada and Michigan, all of which went to Biden. Colorado’s nine presidential electors also went for Biden.

“My constituents deserve to know that the 2020 election was free of fraud,” Lamborn said, despite repeated findings by federal and state elections officials — as well as courts — that there was no widespread fraud.

Boebert has parroted Trump’s unfounded claims that the election was stolen and supports his refusal to concede.

MORE: Colorado’s new members of Congress — John Hickenlooper and Lauren Boebert — are sworn in

Buck, serving his fourth term in Colorado’s expansive 4th District, claimed there were troubling irregularities in the six battleground states without offering evidence. But he rejected the dissidents’ strategy, saying only the states have authority to appoint electors.

“Congress has only the narrow role in the presidential election process. Its job is to count the electors submitted by the states, not to determine which electors the states should have sent,” Buck said in a statement co-signed by six Republican House members.

Colorado’s Democratic attorney general, Phil Weiser, joined elected officials in Wisconsin and Arizona on Monday in condemning the unprecedented move against Biden as undermining the democratic process.

Along with the Constitution, Weiser cited a failed Texas lawsuit that sought to overturn results in four swing states, as well as a Supreme Court ruling reasserting the states’ authority over the makeup of their Electoral College votes.

In a conference call for reporters organized by the Voter Protection Program, a bipartisan, nonprofit group, Weiser called the dissident effort “an affront to the rule of law. It’s a threat to our democratic process. … I’m disheartened by how many people have signed on to this.”