(CNN) Republican Sen. Mitt Romney will not be invited to a major conservative conference following the Utah Republican's vote Friday in support of witnesses during the Senate's impeachment trial, the event's chairman said.

Matt Schlapp, chairman of the Conservative Political Action Conference, tweeted on Friday, "BREAKING: The 'extreme conservative' and Junior Senator from the great state of Utah, @SenatorRomney is formally NOT invited to #CPAC2020."

Romney and Sen. Susan Collins of Maine were the only two Republicans to break ranks and join the chamber's 47 Democrats in voting to allow subpoenas for witnesses and documents, a move that would have extended the trial. The pair's efforts failed, as their fellow potential Republican defectors, Sens. Lisa Murkowski of Alaska and Lamar Alexander of Tennessee, ultimately voted against witness testimony to seal the 51-49 total.

Schlapp's tweet appeared to reference when Romney, while running for president in 2012, infamously said he was "severely conservative" -- not "extremely conservative" -- at CPAC. President Donald Trump has spoken at the conference several times.

CNN reported Friday morning that Romney intended to vote in favor of witness testimony during the trial as expected, according to an aide. During a break in proceedings on Friday evening, Romney, Collins, Murkowski and Alexander were among a number of senators who met with Senate Majority Leader Mitch McConnell, a Kentucky Republican.

Romney had told The New York Times on Thursday that "I know there are some who feel if we open the door, we'd have tons of witnesses and court battles." He told the paper he would suggest that each side get two witness requests and 30 days, procedural delays included, to try and summon them.

The Utah Republican had faced pressure from inside and outside the chamber to change course.

On Monday, Republican Sen. Kelly Loeffler of Georgia alleged on Twitter that "Sadly, my colleague @SenatorRomney wants to appease the left by calling witnesses who will slander the @realDonaldTrump during their 15 minutes of fame."

The conservative group Club for Growth released an ad Wednesday, accusing Romney of joining forces with Democrats during the trial, to air on Fox News in Salt Lake City and Washington. FreedomWorks, another conservative group, bought an ad in The Salt Lake Tribune on Thursday urging Romney to "vote for no new witnesses."