Updated: 11:46 p.m.
GOP leaders may have hoped Tuesday night's deal to lift Sen. Jim Bunning's (R-Ky.) blockade of an extension of unemployment benefits would put an end to the controversy.
But Bunning appears to have other plans, accusing Democrats of violating the deal that prompted him to end his filibuster, and vowing to throw up new filibusters in the future.
Bunning has also reported receiving death threats in recent days, according to informed sources.
The Kentucky Senator expressed bitterness in the wake of Tuesday night's 78-19 vote extending unemployment benefits by a month. President Barack Obama signed the bill into law late Tuesday.
"Democrats tonight showed their true colors by going back on their word on the agreement I had reached with Majority Leader [Harry] Reid (D-Nev.) to have an up-or-down vote on my amendment to fully pay for the unemployment extension and other federal programs," Bunning said in a statement following Tuesday's vote. "Instead, Senate Democrats used a procedural gimmick so they would not have to vote on my pay-for amendment."
"If Democrats continue to ignore their own rules I will oppose future legislation that is not paid for," Bunning added. Additionally, a Bunning aide said the lawmaker would likely take to the Senate floor Wednesday to discuss the situation.
The deal Bunning and Reid cut did allow for an up-or-down vote on his amendment. But because Bunning did not specifically require the unanimous consent agreement to shield the amendment from budget points of order or other procedural hurdles, Sen. Barbara Boxer (D-Calif.) was able to ultimately kill the amendment through a point of order.
A Democratic leadership aide dismissed Bunning's complaints. "He was promised a vote. He got one. The families he put in jeopardy by his reckless actions could care less about his excuses, his contradictory reasoning or his procedural complaints," the aide said.
Meanwhile, Capitol Police are investigating numerous threats that have come into Bunning's office over the past several days in response to his filibuster, sources familiar with the situation said.
A Bunning aide confirmed late Tuesday night that the office had received a number of complaints via phone, fax and e-mail, and that they had been forwarded on to Capitol Police for investigation. "There have been some threats. We take all threats seriously, and we've been reporting them to the authorities," the aide said.
A second source familiar with the situation said Bunning had received a number of death threats.
Obama's decision to sign the bill late Tuesday should mean thousands of federal employees furloughed as a result of the filibuster could be back to work in the next few days.
"During these difficult economic times, supporting American workers, their families and our small businesses must be everyone's focus," Obama said after signing the legislation. "The bill passed tonight by the Senate will extend access to health care benefits for workers who have lost their jobs, help small businesses get loans so they can grow and hire, and extend unemployment insurance benefits for millions of Americans who are looking for work. I'm grateful to the members of the Senate on both sides of the aisle who worked to end this roadblock to relief for America's working families."
Jessica Brady contributed to this report.