On Monday, the Senate plans a test vote, and Majority Leader Harry Reid, D-Nev., has made it clear he expects to get the necessary 60 votes to move ahead on the legislation.
All 55 members of the Senate's Democratic majority are expected to vote "yes" on the test vote, along with four Republicans — Orrin Hatch of Utah, Lisa Murkowski of Alaska and the measure's co-sponsors, Illinois' Mark Kirk and Collins.
Proponents are optimistic that four other Republicans also will support moving ahead: Kelly Ayotte of New Hampshire, Rob Portman of Ohio, Dean Heller of Nevada and Pat Toomey of Pennsylvania.
The Senate could complete the bill by week's end.
The evolution and changing views on gay rights are evident in the senators now expressing support.
In September 1996, the Senate narrowly rejected a similar measure on a 50-49 vote. That bill did not include protections for transgender people. Voting against it were Hatch and then-Alaska Sen. Frank Murkowski, father of Lisa Murkowski. Subsequent efforts over the next 17 years to secure Senate passage of the bill faltered.
This past July, Hatch, Kirk and Lisa Murkowski backed the bill when the Senate Health, Education, Labor and Pensions Committee, led by Sen. Tom Harkin, D-Iowa, endorsed the measure 15-7.
"I think that this issue is not so much a Democrat-Republican issue, although more Democrats are for it of course, as it is an age issue," said Sen. Chuck Schumer, D-N.Y. "You'll find a lot of young people who are very conservative are much more pro-gay rights. There are some who would not support marriage but would support anti-discrimination. For those two reasons, I think we have a good chance of it passing."
Twenty-two states and the District of Columbia have approved laws banning workplace discrimination on the basis of sexual orientation, and 17 of those also prohibit employers from discriminating based on gender identity.
About 88 percent of Fortune 500 companies have already adopted nondiscrimination policies that include sexual orientation, according to the Human Rights Campaign. About 57 percent of those companies include gender identity.
Associated Press writer Catherine Lucey in Des Moines, Iowa, contributed to this report.
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