Senators who support expanding criminal background checks for gun buyers said Tuesday that they intend to revive the legislation for a vote by this summer, though the measure won't be exactly the same as the one senators defeated a month ago.

The Senate last month fell four votes shy of approving landmark, bipartisan legislation authored by Sen. Joe Manchin, D-W.Va., and Sen. Pat Toomey, R-Pa., that would have widened background checks to include firearms bought at gun shows or over the internet.

"Whenever the support and the time is right we will do it," Manchin said Tuesday.

Senate Majority Whip Dick Durbin, D-Ill., who sets the chamber's floor schedule, told The Washington Examiner a bill could be brought up "at a moment's notice" and very soon.

"When we have five [additional] votes, it's time to call it," Durbin said.

Advocates for expanded background checks believe they have a better chance of succeeding now because a number of senators who helped kill the measure last month saw their poll numbers take a sudden plunge. The checks have up to 90 percent of the public's support in some polls following the massacre of school children at Sandy Hook Elementary School in Connecticut in December.

"The increasing fury back in the states is giving people a reason to think twice about this issue," Sen. Chris Murphy, D-Conn., said Tuesday.

Supporters need 60 votes to advance background checks in the Senate, which means they must get five lawmakers to reverse their votes. To do that, lawmakers said some provisions may need to be rewritten to meet concerns those lawmakers have, like exempting online gun purchases between friends.

"We can't bring back the bill as is," Murphy said. "There are plenty of ways in which you can change the background check piece of the bill to allay those concerns."

He said other changes could include excluding gun buyers in rural areas and adding a provision that addresses mental health aspects of gun violence. Those issues were a big concern to Sens. Jeff Flake, R-Ariz., and Kelly Ayotte, R-N.H., two opponents who could reverse their votes.

Both Flake and Ayotte Tuesday denied reports that angry constituents are driving them to to reconsider their votes against the first background check measure.

Flake saw his approval rating plummet after he voted against the Toomey-Manchin measure in April.

"I voted against that for a reason and I'm not reconsidering my vote," Flake said Tuesday.

Flake said he opposed the definition of commercial sales in the original bill because he believed it was too broad and included, for example, sales on Craigslist.

"I doubt they could change it sufficiently [to win him over] because then they would lose votes on the Left," Flake said.

Ayotte, who was confronted about background check legislation by angry constituents at a recent town hall meeting, said she would consider new legislation if it's changed to meet her concerns.

"I support a bipartisan bill that would improve the background check system," Ayotte said. "I've supported and worked across the aisle on mental health issues, which is important, if we are going to address the underlying causes of violence. And increase resources for prosecution for these types of crimes."