The Senate inched closer to filibuster-proof support for the Employment Non-Discrimination Act on Wednesday, with the last Democratic holdout, Sen. Joe Manchin III, D-W.Va., announcing his intent to back the bill.

Senate aides indicated that Majority Leader Harry Reid, D-Nev., likely will bring the legislation to the floor within the next two weeks — possibly as early as next week.

With Manchin’s commitment and Sen.-elect Cory Booker, D-N.J., being sworn in Thursday, supporters of the bill to ban workplace discrimination on the basis of sexual orientation now have 59 votes for their cause. That includes three Republicans who voted for it in committee — Sens. Lisa Murkowski of Alaska, Mark S. Kirk of Illinois and Orrin G. Hatch of Utah — and Maine GOP Sen. Susan Collins.

A source tracking the bill said that ENDA supporters now are targeting Republicans Kelly Ayotte of New Hampshire, Dean Heller of Nevada, John McCain of Arizona and Patrick J. Toomey of Pennsylvania, in addition to Rob Portman of Ohio, the first GOP senator to back gay marriage.

Manchin’s decision Wednesday, first confirmed by The New York Times, made it that much more likely that ENDA will pass the Senate. “There’s no way that I could ever not support something that basically bans discrimination,” Manchin told the Times.

In 2010, Manchin missed a vote on repealing “don’t ask, don’t tell” to attend a Christmas party, announcing afterward that he would not have supported the repeal had he been in Washington.

In an emailed statement to CQ Roll Call, Manchin said of his ENDA decision Wednesday: “After careful review of the Employment Non-Discrimination Act to make sure that this bill will not create preferential treatment for certain individuals nor limit the First Amendment protections of religious institutions, I plan to support this important piece of legislation.”

Though ENDA supporters in the Senate are bullish on their chances for passage in their own chamber, they are less optimistic about the bill’s chances in the Republican-controlled House.

The more Republican senators ENDA advocates can get to back the bill, the more pressure they could put on Speaker John A. Boehner, R-Ohio, to bring the legislation to the House floor. But even that might not be enough, given the current political realities of the House Republican caucus.

“We’re not at a place where a certain threshold in the Senate guarantees anything in the House,” a House Republican aide said.