WASHINGTON – Even Republicans who have pushed for tighter gun restrictions blasted President Barack Obama on Tuesday for bypassing Congress with an executive order toughening background checks for gun sales.

Pennsylvania Sen. Pat Toomey, a Republican who sponsored an unsuccessful bill last year requiring background checks at gun shows, said he still supports efforts to “keep guns out of the hands of criminals and the mentally ill.”

But he said in a statement that Obama has “abused” executive actions in the past and “exceeded the boundaries of the law.”

“This should not be allowed under our constitutional framework,” he said.

Sen. Roy Blunt, R-Missouri, who sponsored a bill last year to increase mental health services that he said would get at the root causes of gun violence, likewise criticized Obama.

“There seem to be no limits to how far this president will go to overstep the Constitutional limits of his power. His latest target is the Second Amendment rights of law-abiding Americans,” Blunt said.

In addition to tightening background checks at gun shows and for online sales, Obama wants to spend $500 million to increase access to mental health care.

He directed the Social Security Administration to add beneficiaries who are not allowed to have firearms for mental health reasons into the national background check system.

Obama’s order also removes legal barriers that prevent states from reporting information about people with mental health issues into the database.

Guidance released by the Bureau of Alcohol, Tobacco, Firearms and Explosives in conjunction with Obama’s order interpreted an existing law that gun control groups have criticized as too vague.

The law had required only those “engaged in the business” of selling firearms to conduct background checks. Gun control advocates say the vagueness of the term has kept prosecutors from winning convictions or even bringing cases against people accused of selling guns to felons, the mentally ill or others barred from buying weapons.

The ATF said this week that all commercial sales are now subject to background checks, though it did not specify how many sales per year would require a dealer to conduct background checks, as gun control groups wanted.

Rather, the ATF said a number of factors are considered in determining whether gun-sellers must screen buyers, including whether sellers represent themselves as firearms dealers, and whether they are trying to profit.

The National Rifle Association did not respond to a request for comment.

The group’s former assistant general counsel, David Hardy, now in private practice in Tucson, Arizona, said he is less concerned about ATF considering a gun-seller’s profit motive, which it can already do.

But he questioned using Social Security’s disability data.

The law now prohibits gun ownership for those who have been hospitalized for mental illness or found to be “mentally defective.” Wrapping in those on disability for mental health reasons seems “questionable,” he said.

The ATF, he said, “has historically tended to get out of control. If you give them too much encouragement, they might do so again.”

Obama’s executive order was hailed by gun control advocates including Sen. Elizabeth Warren, D-Massachusetts, who wrote on Twitter, “If Congress won’t step up to keep our kids safe, somebody else needs to start.”

Sen. Edward Markey, D-Massachusetts, applauded an aspect of Obama’s order that directs agencies to look into ways to further the use of smart guns, which use fingerprints and other means to allow only authorized users to fire a weapon.

“All of the actions announced today will go a long way to responding to the tragedies that Republicans in Congress continue to allow unabated through their consistent opposition to passage of common-sense gun safety legislation,” Markey said.

Toomey’s seat-mate, Sen. Robert Casey, D-Pennsylvania, called the moves “common-sense steps.”

“Pennsylvania has a rich tradition of hunting,” Casey said, “and I believe that people should be able to have guns for protection, sporting and collection. But I also believe we need sensible gun legislation that will help to prevent these tragedies.”

Senate Majority Leader Mitch McConnell said Congress will examine Obama’s directives “to determine whether they follow federal law and the Constitution.”

He also said, in a statement, “In the wake of the president’s vow to ‘politicize’ shootings, it’s hard to see today’s announcement as being about more than politics.

“At a time when the American people are looking to the commander in chief to provide real leadership in countering terrorist threats from ISIL and al-Qaida, what Americans seem to get instead are lectures, distractions and attempts to undermine their fundamental, Second Amendment rights,” McConnell said.

Kery Murakami is the Washington, D.C., reporter for CNHI’s newspapers and websites. Reach him at kmurakami@cnhi.com

Sen. Jeff Sessions: How many thousands of lives would be saved if we enforced our immigration laws, our guns laws, and our drug laws? Public safety is not being held hostage by the ‘gun lobby,’ but by the open borders lobby and the anti-law enforcement lobby.

Gov. Robert Bentley: America’s founding fathers prioritized the right to keep and bear arms, and President Obama is overstepping his authority and threatening to take away our 2nd amendment rights. It is unacceptable for the President to bypass Congress and the U.S. Constitution with his plan.

Rep Gary Palmer: The President’s Executive Actions are beyond the scope of his Constitutional powers. This President has developed a pattern over the past seven years of ignoring the Constitution whenever it suits him. This is wrong. Nothing in the President’s Executive Actions would have done anything to stop the most recent incidents of gun violence.