House Speaker Paul Ryan on Monday warned President Obama that the nation "will not stand for" presidential overreach that restricts gun ownership.
Ryan, R-Wis., said he believes Obama is "subverting the legislative branch," by proposing stricter gun laws, including regulations expanding background checks.
Obama will meet Monday with Attorney General Loretta Lynch to discuss gun control measures he can enact without the approval of Congress, which has rejected any expansion of background checks or restrictions on guns or ammunition.
Obama is expected to announce his plan this week.
The Senate in 2013 rejected legislation to expand background checks for gun purchases and to ban some types of semi-automatic weapons and ammunition.
"While we don't yet know the details of the plan, the president is at minimum subverting the legislative branch, and potentially overturning its will," Ryan said. "His proposals to restrict gun rights were debated by the United States Senate, and they were rejected. No president should be able to reverse legislative failure by executive fiat, not even incrementally."
Ryan said Congress should instead address mental illness, which has been blamed for many of the mass killings carried out in the United States in recent years, including the deadly Sandy Hook Elementary School shooting in 2013.
Lawmakers in the House and Senate are working on legislation that would help ensure the mentally ill do not obtain guns.
"We have seen consistently that an underlying cause of these attacks has been mental illness, and we should look at ways to address this problem," Ryan said.