WASHINGTON (NewsNation Now) — President Joe Biden on Tuesday called for a ban on assault weapons and tighter gun control measures the day after police say a gunman opened fire on a Colorado supermarket, killing 10 people.

“I don’t need to wait another minute, let alone an hour, to take common sense steps that will save lives in the future,” Biden said, urging his “colleagues in the House and Senate to act.”

“We can ban assault weapons and high capacity magazines in this country, once again,” he said.

The president specifically called for closing loopholes in the U.S. background check system.

“That’s one of the best tools we have right now, to prevent gun violence,” he said.

Biden addressed the nation from the White House Tuesday, before traveling to Ohio, where he’ll mark the 11th anniversary of the signing of the Affordable Care Act.

Biden said that the mass shooting in Colorado took place “while the flag was still flying half staff” for the series of shootings at three spa businesses in the Atlanta area, which left eight dead. Six of the victims were Asian women.

“This is not and should not be a partisan issue,” Biden said about tighter gun control measures on Tuesday. “It’s an American issue that will save lives, American lives. We have to act.”

Biden, who took office in January, faces an uphill battle in winning congressional approval for gun-related measures he pledged during his presidential campaign.

The House on March 11 passed two bills that would broaden background checks for gun buyers, but the legislation faces an uncertain future in the Senate.

Most legislation requires 60 votes in the 100-seat chamber to move forward. With the Senate divided, reaching that threshold appears difficult.

A Senate panel held a hearing on gun issues on Tuesday. Biden has not put forth his own legislation but issued statements of support for the House-passed bills and called for Senate passage.

Any potential gun control measures passed by Congress would almost certainly face a legal challenge that could reach the Supreme Court, whose 6-3 conservative majority is seen as sympathetic to an expansive view of gun rights.

Senate Majority Leader Chuck Schumer vowed Tuesday morning to bring to the Senate floor legislation passed by the House that would require background checks for most gun sales and transfers. He said the Senate “must confront a devastating truth” after a lack of congressional action on the issue for almost three decades.

“This Senate will be different,” said Schumer, D-N.Y. “The Senate is going to debate and address the epidemic of gun violence in this country.”

Connecticut Sen. Richard Blumenthal, who’s pushed for expanded gun control since the 2012 shooting at Sandy Hook Elementary School that killed 20 children and six educators, has expressed optimism about the chances for new laws with President Joe Biden in the White House and Democrats controlling the House and the Senate. He called it “the dawn of a new era.”

But change does not come easy in the Senate. Republican Sen. Pat Toomey of Pennsylvania and Democratic Sen. Joe Manchin of West Virginia have worked together for years to find compromise on background checks but have yet to propose anything that will pass. Many in the GOP base are still strongly opposed to gun control of any kind.

Recently Toomey joined Senators Chris Coons (D-Del.) and John Cornyn (R-Texas) to reintroduce gun safety legislation that will help states enforce existing laws against individuals who attempt to purchase firearms by lying on their background check.

A spokesman for Toomey said earlier this month, the senator remains supportive of a previous bipartisan proposal with Manchin but believes “progress is only possible on this issue if the measure in question is narrow and protects the rights of law-abiding gun owners.”

The spokesman, Steve Kelly, did not say whether the House bills meet that standard.

And in Tuesday’s hearing, which was scheduled before the Colorado shooting, some Republicans showed no signs of wavering. Texas Sen. Ted Cruz said that every time there is a shooting, the Senate engages in “ridiculous theater,” with Democrats proposing laws that he said could take guns away from law-abiding citizens. Republicans have argued that background checks would not stop most mass shootings and would prevent some lawful gun owners from purchasing firearms.

“We already know this pattern is predictable, over and over and over again,” Cruz said.

Legislation passed by the House two weeks ago would close loopholes to ensure background checks are extended to private and online sales that often go undetected, including at gun shows. The legislation includes limited exceptions allowing transfers of firearms that are gifts from family, that are to prevent imminent harm or that are for use at a target range, among others.

A second bill would extend a review period for background checks from three to 10 days. Rep. Jim Clyburn, D-S.C., introduced the legislation after a shooter killed nine people at a Charleston, South Carolina, church in 2015. The FBI said afterward that a background check examiner never saw the shooter’s previous arrest report because the wrong arresting agency was listed in state criminal history records, and the gun dealer was legally permitted to complete the transaction after three days.

The Associated Press and Reuters contributed to this article. All reporting by AP’s Mary Clare Jalonick and Reuters’ Trevor Hunnicutt, Jeff Mason and Nandita Bose.