Illinois Sen. Mark Kirk announced Thursday that he would vote to confirm Loretta Lynch as U.S. Attorney General, becoming the fifth Republican to voice support for the stalled nominee.

Kirk's declaration means that Lynch, now a U.S. Attorney for the Eastern District of New York, apparently has the 51 votes needed for confirmation.

"I am confident from my conversation with Loretta Lynch that she will be a valuable partner in confronting the gang violence that is robbing families of their children every day in Chicago," Kirk said in a statement. "We need the help of the Attorney General to fight gangs of national significance through federal law enforcement agencies and prosecutors, and to address organized crime like drug and child sex trafficking."

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Earlier on Thursday, New Jersey Sen. Bob Menendez, a Democrat, also said he would vote to confirm Lynch. There was some earlier speculation that Menendez would recuse himself from the vote - and deprive Democrats of a crucial vote - because of Lynch's role in a criminal probe bedeviling the senator.

Aides to Menendez, who was indicted Wednesday on corruption charges, said the senator "looks forward to voting for Ms. Lynch when her nomination comes to the floor."

Lynch enjoys unanimous support from the Senate's 46 Democrats. Among Republicans, she's received the public backing of Sens. Orrin Hatch, R-Utah, Lindsey Graham, R-South Carolina, Jeff Flake, R-Arizona, Susan Collins, R-Maine, and Kirk.

President Obama first nominated Lynch last November after current Attorney General Eric Holder announced in September that he would step down when a successor is confirmed. The president urged the Senate to confirm her "without delay," but more than 140 days have passed since then, making Lynch the longest pending attorney general nominee in more than three decades.

Senate Minority Leader Mitch McConnell, R-Kentucky, has blamed the delay on a dispute over a human-trafficking bill that drew opposition from Democrats due to its inclusion of anti-abortion language.

"I wanted to hold a vote on the attorney general, but if I can't get this bill through first then I'm going to have to delay the confirmation vote," McConnell told CNN earlier this month.

The slow timeline has been a source of deep frustration for the White House and Democrats on Capitol Hill.

"No one can claim she's unqualified. No one's saying she can't do the job. Senators from both parties say they support her. This is purely about politics," the president said on March 21.

"Loretta Lynch, the first African-American woman nominated to be attorney general, is asked to sit in the back of the bus when it comes to the Senate calendar," said Sen. Dick Durbin, D-Illinois, several days earlier. "That is unfair. It's unjust. It is beneath the decorum and dignity of the United States Senate."

CBS News' John Nolen contributed to this report.