Connecticut's Democratic Sens. Chris Murphy and Richard Blumenthal are frustrated by the inability of Congress to pass more gun control laws and want President Obama to go it alone.

Both senators have called on Obama to take executive action to close a loophole in the federal gun legislation.

The Hill reported Saturday that the senators demanded the president reform the so-called "default to proceed" rule under the Brady Handgun Violence Prevention Act. The rule mandates that firearm dealers must request a background check to the FBI but if the bureau cannot complete it in three days, the dealer has the discretion to sell the weapons.

It was this "loophole" that allowed Dylann Roof to purchase a gun even though he had a felony drug charge.

"We shouldn't give known criminals the benefit of the doubt when it comes to guns. If law enforcement needs more than three days to ensure they're not giving weapons to dangerous people, Washington must allow them the time to do their jobs. If we refuse to act, we're just biding time until this happens again," Blumenthal and Murphy said in a statement. 

The criminal background check on Roof did not reveal his arrest until five days after the firearm dealer initiated the background check.

“[Roof] should not have been allowed to purchase the gun he allegedly used that evening,” FBI Director James Comey said to reporters on Friday.

Republicans have dismissed these claims, blaming bureaucratic failings, not the current gun laws.

“It’s disastrous that this bureaucratic mistake prevented existing laws from working and blocking an illegal gun sale. The facts undercut attempts to use the tragedy to enact unnecessary gun laws,” said Senate Judiciary Committee Chairman Chuck Grassley (R-Iowa) in a statement.