WASHINGTON – A vote on the nomination of B. Todd Jones to become permanent director of the Bureau of Alcohol, Tobacco, Firearms and Explosives could come as soon as Wednesday.

Senate Majority Leader Harry Reid moved Monday to force a vote on Jones' nomination this week over the objection of Sen. Chuck Grassley, the lead Republican on the Senate Judiciary Committee.

After implying last week that he might not block Jones' nomination, Grassley reaffirmed his opposition to Jones on Monday, setting up a Senate showdown over one of President Obama's most hotly contested nominees.

Minnesota's Democratic Sens. Amy Klobuchar and Al Franken, both members of the judiciary panel, voted for Jones' nomination. Optimistic about his chances before the full Senate, the pair also recommended that Obama nominate trial lawyer Andrew Luger to succeed Jones as the state's next U.S. attorney.

Klobuchar applauded Reid's decision to force a vote Monday, saying the ATF needs a permanent leader.

But hurdles remain.

Facing a potential GOP filibuster, Senate Democrats would have to secure at least six Republican votes to install Jones as the permanent head of the ATF, an agency he has led as acting director for the past two years.

Jones was not among the nominees that senators agreed upon earlier this month as part of a compromise to work around the mass filibustering of presidential nominees.

The nomination battle also has played out against the backdrop of Obama's gun control agenda after the December school massacre in Newtown, Conn. Jones was tapped to lead the ATF's recovery from the controversial "Fast and Furious" gun-tracking case in Arizona, which led to the death of a Border Patrol agent. The episode became a rallying point of Republican criticism of the Obama administration.

The Senate hasn't confirmed a director of the agency in six years and Republican lawmakers such as Grassley have lingering concerns about Jones.

During a floor speech Monday, Grassley cited an investigation by the U.S. Office of Special Counsel, which is looking into allegations that Jones retaliated against a whistleblower in the U.S. attorney's office for Minnesota. He and the whistleblower, Assistant U.S. Attorney Jeff Paulsen, have entered into mediation.

Republicans and Democrats have disagreed on whether Jones' nomination should proceed before the matter is resolved.

"The Senate should wait until the Office of Special Counsel has concluded its investigation, and we know the truth," Grassley said on the Senate floor Monday.

Jones' nomination advanced past the Judiciary Committee on a 10-8 party-line vote.

Corey Mitchell is a correspondent in the Star Tribune Washington Bureau. Twitter: @C_C_Mitchell