WASHINGTON – Senate Democrats plan to introduce a package of bills today to tighten gun laws – and pile pressure on vulnerable Republicans -- but Pennsylvania Sen. Pat Toomey, who in 2013 was a key Republican on the issue and faces re-election next year, said Thursday he was worried about the "partisan" effort now being advanced.

"While I welcome the renewed interest of my senate colleagues in this critical issue, I worry that a partisan and unbalanced approach will receive even less support than the 54-vote majority the Manchin-Toomey amendment received," Toomey said in a statement Thursday morning, ahead of a Democratic news conference. He was referring to the bill he co-sponsored with Sen. Joe Manchin (D., W. Va.) that would have expanded background checks in the aftermath of the 2012 Sandy Hook School hooting.

A spokeswoman said Toomey was not consulted on the new Democratic-led push.

The 2013 background check bill, which won Toomey widespread praise as a rare Republican willing to cross party lines on gun laws, was blocked because it needed 60 votes to pass. The defeat, after a stunning mass killing, was a major setback for advocates of new gun laws.

Toomey has highlighted the bill as an example of his willingness to compromise in a dysfunctional Senate, but Democrats have questioned his commitment, noting that he has not reintroduced the bill since it failed.

The recent massacre at an Oregon college has brought the issue racing back to the forefront.

Democrats know they have no chance of passing new gun laws in a Republican-controlled Senate, one that is now more conservative than the one that blocked Toomey's original plan, but they hope to use the issue to show the divide between the two parties as they head into high-stakes elections in 2016. Toomey's Pennsylvania race could be one of a handful that determine control of the Senate.

Senate Democrats have a 11 a.m. press conference Thursday to unveil their new bills.

Toomey said his 2013 measure was "balanced" with expanded background checks and new protections for lawful gun owners. "I continue to strongly support that approach," he said.

He has repeatedly said he would like to advance his background check bill or a version of it if possible, but that there is no realistic path forward right now in the Senate.

He has given no indication of plans to reintroduce the measure – prompting Democratic criticism.

"If you are truly committed to doing the right thing – and you truly believe in your efforts – you do not let failure deter you," Democratic Senate candidate Katie McGinty wrote to Toomey Monday. "Last week's event in Oregon serves as a tragic reminder that we cannot give up when it comes to making our communities safer from the scourge of gun violence."

Toomey is looking for ways to "move the ball forward, including the option of reintroducing the bill," said his spokeswoman, E.R. Anderson.

Another potential Democratic rival, Joe Sestak, has made similar comments and a third Democratic candidate, Braddock Mayor John Fetterman, also supports tighter gun laws.

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