The House Ethics Committee announced Friday that it is upholding the $500 fines issued to a handful of GOP lawmakers who refused to comply with a requirement last month to wear masks on the House floor during the COVID-19 pandemic.

Reps. Brian Mast (Fla.), Beth Van Duyne (Texas) and Mariannette Miller-Meeks (Iowa) were among at least six House Republicans who joined in a protest last month against the requirement that everyone wear masks in the House chamber regardless of vaccination status.

The House ultimately lifted the mask requirement earlier this month in accordance with guidance from the Capitol physician that it was safe to follow the Centers for Disease Control and Prevention (CDC) announcement that people fully vaccinated against COVID-19 could forgo masks in most settings.

Mast and Van Duyne both filed appeals with the House Ethics Committee, but their efforts were rejected, the panel announced Friday. A majority of the evenly divided committee, which consists of five Democrats and five Republicans, must agree in order for an appeal to succeed.

Mast and Van Duyne both wrote in their appeals that they are fully vaccinated and "followed the science." They also argued that the fines violate the Constitution's 27th Amendment, which prohibits any change to the salaries of members of Congress until an election has passed.

"It's evident now that enforcement of any mask rule has become a partisan, political issue, rather than one grounded in science," Van Duyne wrote in her appeal.

Miller-Meeks, meanwhile, did not file an appeal with the House Ethics Committee. A spokesperson didn't immediately return a request for comment from The Hill on why she had not.

Three other House Republicans said last month that they had also been issued fines: Reps. Marjorie Taylor Greene (Ga.), Thomas Massie (Ky.) and Ralph Norman (S.C.).

After the CDC's new guidance was issued May 13, the Capitol physician initially maintained that lawmakers should still wear masks on the House floor because it is "the only location where the entire Membership gathers periodically throughout the day in an interior space."

In new guidance issued June 11, the Capitol physician said that only people who are unvaccinated or "vaccination-indeterminate" should continue to wear masks.

But mask rules are no longer being enforced in the House. Most members of both parties have not been wearing masks around the Capitol in recent days.

Masks have been a divisive issue in the House since the start of the pandemic last year, straining already fraught relations between the two parties.

Speaker Nancy Pelosi (D-Calif.) instituted the mask requirement in July after dozens of House Republicans refused to wear face coverings voluntarily, including one who subsequently tested positive for COVID-19 after spending time on the floor and in committees in proximity to other lawmakers. Pelosi warned that any lawmaker refusing to wear a mask would be removed from the House floor by the sergeant-at-arms.

Then in January, Democrats voted to make the House floor mask requirement punishable by fine — $500 for the first offense and $2,500 for subsequent offenses — after three of their members tested positive for COVID-19 after spending hours in a crowded secure space during the Jan. 6 insurrection with several maskless Republicans.

Another safety measure instituted after Jan. 6 is also enforceable by fines instituted by Democrats. Lawmakers who fail to complete metal detector screenings prior to entering the House chamber are subject to a $5,000 fine on the first offense and $10,000 for the second.

Six lawmakers to date have been issued metal detector fines. The House Ethics Committee upheld the fines issued against Republican Reps. Louie Gohmert (Texas) and Andrew Clyde (Ga.), but agreed to dismiss the fines issued to House Majority Whip James Clyburn (D-S.C.) and Rep. Hal Rogers (R-Ky.).

Gohmert and Clyde filed a lawsuit in federal court last week to challenge the constitutionality of the fines.