Seven thousand pairs of shoes, representing the children killed by gun violence since the mass shooting at Sandy Hook Elementary School in 2012, are spread out on the lawn on the east side of the U.S. Capitol March 13, 2018 in Washington, DC.

The House passed its second bill this week to strengthen gun background checks, in the biggest gun control push Congress has made in more than 20 years.

The Democratic-held chamber approved a plan Thursday to extend the background check review period to 10 days from three days. It passed in a 228-198 vote, as three Republicans backed it. A day earlier, the House cleared a measure to require checks for all firearms sales, including those purchased online and at gun shows.

President Donald Trump has promised to veto both proposals, arguing they would restrict the rights of gun owners. The legislation is unlikely to get through the GOP-controlled Senate.

Though the proposals may not become law, they mark the most significant congressional movement on gun control since lawmakers passed an assault weapons ban in 1994. That law eventually expired.

House Speaker Nancy Pelosi and the Democratic caucus pledged to take steps to address gun violence when they took control of the chamber in January for the first time in eight years. They have in part cited a string of prominent mass shootings around the country.

They were bolstered in part by several candidates who featured gun control prominently in their campaigns winning swing GOP-held House districts in November's midterms.

Public opinion in the U.S. has moved in favor incremental gun control steps. Last month, a Quinnipiac University survey found 92 percent of Americans say they favor background checks for all gun sales.

Democrats said the bill approved Thursday would close the so-called Charleston loophole. The shooter who massacred nine black parishioners in a South Carolina church in 2015 was able to buy a gun when the FBI did not finish his background check within the three-day period.

House Majority Whip James Clyburn, D-S.C., pushed for the proposal passed Thursday. He represents large parts of Charleston.

The White House argues the bills would put an unnecessary burden on gun owners. Some Democrats have accused Trump of hypocrisy after he said he would be "very strong on background checks" after the shooting deaths of 17 students and staff members at a Florida high school last year.

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