WASHINGTON - The Orlando shooting that left 50 dead Sunday immediately brought new calls for tougher gun laws from Sen. Bob Casey (D., Pa.), who plans to introduce a bill Monday to ban anyone convicted of misdemeanor hate crimes from purchasing firearms.

Currently, only those convicted of a felony face such bans.

Casey is scheduled to introduce his measure at a Pittsburgh news conference. He was among several officials from the Philadelphia area who said the latest mass shooting shows the need for tighter regulation of gun purchases.

"We must take every step to keep America safe, which means targeting and taking out terrorists while keeping guns out of the wrong hands," Casey said in a news release. "It's time for Congress to finally act on gun violence and ban military-style weapons, put limits on clips and magazine sizes, ban those on the terrorist watch list from purchasing firearms, and require background checks on all gun sales. We know that the shooter in Orlando used a high-powered weapon that allowed him to fire a large number of bullets in rapid succession."

His bill would address a more narrow issue: adding federal and state hate crimes to the list of convictions that can be used to stop people from buying guns.

Casey, who once opposed new gun laws, changed his stand after the 2012 Sandy Hook school massacre in Newtown, Conn. That shooting led to the last major congressional effort for tougher laws, a failed move to expand background checks and ban so-called assault weapons and high-capacity magazines. It also showed the limits of calls for new bills - none was enacted, and the odds of any passing the Republican-controlled Congress now are slim.

Sen. Pat Toomey (R., Pa.) drew national attention during the post-Newtown gun debate by becoming the sole Republican to co-sponsor a bill to broaden background checks. That stand has become a key selling point in his re-election bid this year. His initial reaction to Sunday's shooting, however, focused on the victims and made no mention of new laws.

"My heart goes out to the loved ones of those murdered at the nightclub in Orlando," Toomey wrote on Facebook. "I extend my condolences to the family and friends of those killed, and I am praying for the wounded who are undergoing medical treatment."

Other local lawmakers, including some who support stronger gun laws, also offered condolences.

"Deeply appalled & saddened by the innocent murders in #Orlando. My prayers are with the victims of this hate crime and act of terrorism," Rep. Bob Brady (D., Pa.) wrote on Facebook.

Writing on Twitter, Rep. Pat Meehan (R., Pa.) called the shooting "heartbreaking" and offered prayers to the victims and their families.

And at a gay pride festival in North Jersey, Sen. Cory Booker (D., N.J.) told reporters that Americans cannot allow one "malicious, vicious, hateful terrorist [to] take away what makes us great as a nation."

But some argued for legislative action.

Pennsylvania State Rep. Steve Santarsiero, a Democrat running for Congress in a Bucks County-based race, promised to "carry on the long fight for sensible gun safety laws and to keep weapons of war out of the hands of violent extremists."

Rep. Bonnie Watson-Coleman (D., N.J.), called for lawmakers to "seize this moment of grief and transform it into action, taking concrete, logical steps to keep guns out of the hands of terrorists and others who shouldn't have access to weapons, and certainly not guns built to deal as much damage as possible."

CeaseFirePA, a gun control group, led a Harrisburg rally in May urging lawmakers to expand the Pennsylvania background check system to cover private sales of long guns. But its proposal has gone nowhere, and instead some House Republicans have backed a plan to eliminate the state's background check system, arguing that approval delays harm potential gun owners.

New Jersey has some of the country's strictest gun laws, but Gov. Christie has vetoed several Democratic attempts to make them even tighter, including in May, when he blocked a bill that would require people convicted of domestic violence or facing a restraining order to surrender their guns. His administration has pushed new rules to make it easier for New Jerseyans to obtain permits to carry concealed handguns, but the Democratic-led legislature has moved to stop those changes.

In Congress, Republicans and some Democrats worry that new restrictions would infringe on Second Amendment rights without preventing shootings. And Congress has only grown more conservative since the push after Newtown fell short.

The last drive in Congress for new restrictions was a politically charged proposal Democrats made in December to bar anyone on the U.S. terrorist "no-fly" list from buying firearms. The bill was blocked by Republicans, including Toomey, who worried that it would unfairly affect people wrongly included on the list.

Toomey and other Republicans instead backed a less stringent GOP alternative.

@JonathanTamari

Staff writers Angela Couloumbus and Andrew Seidman contributed to this article.