WASHINGTON – Senate Majority Leader Mitch McConnell faced a backlash on Twitter Sunday after tweeting that he stood with law enforcement and offered prayers to the victims of violence in El Paso.

"We stand with law enforcement as they continue working to keep Americans safe and bring justice," McConnell said in a tweet that was met by an online backlash by politicians who were calling for Congress to react to the shootings with legislation.

McConnell called said the violence was "sickening" in that same tweet.

Rep. Katie Hill, D-Calif., said "shame on you," calling on McConnell to take up the House's gun violence prevention bills.

No sign of a vote:McConnell silent on calls for special Senate session on guns after mass shootings

Senate Minority Leader Chuck Schumer, D-N.Y., called on McConnell to cancel the Senate's summer recess and reconvene to pass gun control legislation.

"@SenateMajLdr McConnell must call the Senate back for an emergency session to put the House-passed universal background checks legislation on the Senate floor for debate and a vote immediately," wrote Schumer on Twitter.

The Kentucky Republican has blocked gun control legislation in the Senate that had previously passed the House by wide margins. McConnell had the billsplaced on the Senate calendar, rather than having them referred to a committee to potentially be passed by the full Senate. Here's what that legislation would do.

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H.R. 8: Bipartisan Background Checks Act of 2019

In February this year, the House of Representatives passed H.R. 8: Bipartisan Background Checks Act of 2019. This bill passed 240-190, with eight Republicans joining almost all Democrats to vote for the bill.

This bill would prohibit most person-to-person firearm transfers unless a background check can be conducted, aiming to close a potential loophole allowing the transfer of firearms without a background check at gun shows or between individuals.

The Senate has not taken any action on the bill since the House passed it.

H.R. 1112 Bipartisan Background Checks Act

This bill would extend to at least 10 days the amount of time firearms dealers must wait for a response from the background check system before the sale can proceed. Currently, they can make the sale if they haven’t received a response in three days.

H.R. 1112 passed in February 2019 by a vote of 240-190. Like H.R. 8, the Senate has taken no action on the bill since it passed.

"Red-flag" laws

Some Republicans have spoken in favor of "red-flag" laws, which would allow family members or law enforcement to limit a person's access to firearms if they are deemed a potential threat to the public.

Sen. Lindsey Graham, R-S.C., tweeted in favor of such laws after the Dayton shooting, though he added in a later tweet that such laws "may not have mattered here."

Presidential adviser and eldest daughter of Donald Trump Ivanka Trump tweeted in favor of "red-flag" laws later Sunday.

Assault weapons bans

The Violent Crime Control and Law Enforcement Act of 1994, lapsed in 2004. This legislation, among other provisions, banned the manufacture and sale to civilians of assault-style weapons and certain "large-capacity" ammunition magazines for guns, Congress has attempted to pass new bans on assault-style weapons, but the legislation has picked up little traction in the Republican-controlled Senate.

In March 2019, the Trump administration banned "bump stocks," or attachments that could allow semiautomatic rifles to mimic automatic weapons, after an October 2017 mass shooting in Las Vegas involving a rifle modified with a bump stock killed 58 people.

Contributing: Maureen Groppe