Via Twitter, above is a shot of the standing-room-only crowd tonight in the gallery of the Washington Senate, which is reportedly set to debate and vote on a marriage equality bill at 8 p.m. Central time (6 p.m. Pacific).

We’re told you’ll be able to watch the proceedings live here. The Twitter hashtag is #WA4M.

The bill is widely expected to pass both the Senate tonight and the House at a later date. Gov. Christine Gregoire supports the bill and would sign it. However, Washington is a referendum state so once the bill becomes law, the opposition will have until June to collect 120,557 valid signatures to put the issue on the November ballot.

UPDATE, 8:05 p.m.: The Senate convened at 8 p.m. Dallas time but quickly stood at ease so the two parties could caucus. The Senate is expected to reconvene shortly.

UPDATE, 8:50 p.m.: The Senate has reconvened and is working its way through several amendments to the bill, many of which deal with exemptions for religious institutions.

UPDATE, 10 p.m.: The Senate voted 28-21 to approve the bill. Here’s a press release from Washington United for Marriage:

Washington State Senate Approves Historic Legislation Legalizing Same-Sex Marriage
Bill passes 28-21 on bipartisan vote; house approval expected as soon as next week

OLYMPIA – Washington United for Marriage, a broad statewide coalition of organizations, congregations, unions and business associations that will work to obtain civil marriage for lesbian and gay couples in Washington State in 2012, today cheered the Washington State Senate’s vote in favor of legalizing same-sex marriage legislation in Washington State.  The measure passed by a bipartisan vote of 28-21, with 23 Democrats and four Republicans joining together to advance the bill.  

“We thank Majority Leader Brown, Sen. Murray and the bipartisan coalition of senators who stood with us today in the name of equality,” said Lacey All, Chair of Washington United for Marriage.  “The overwhelming support we’re seeing from businesses, labor, faith communities and people all across the state is a testament to the momentum of this movement and sensibilities of Washingtonians.  Volunteers from every part of the state have contributed thousands of hours of their time to make today possible, and we thank them for their commitment to this issue.”

“As small business owners who pride ourselves on contributing to our community, we are so grateful that today has arrived, and especially for the support of our senator, Mary Margaret Haugen,” said Larry Lowary and Gerry Betz, longtime residents of Washington who live on Whidbey Island.  “We’ve been together for 23 years and entered into our domestic partnership five years ago.  Now we’re looking to the day when we’ll be able to look into each other’s eyes, exchange our vows and finally say ‘I Do’ just like anybody else.”

“The action of the senate today means so much to us, and we thank all the senators who supported this legislation” said Tara Wolfe and A.J. Stolfus, longtime partners from Olympia.  “We moved to Washington years ago in part because of the open and welcoming nature of the people here – something we didn’t always see in Kansas.  We’re simply overjoyed that our friends, family and neighbors can soon recognize us as spouses and our family as being whole.”

The bill now awaits final house approval, which could come as early as next week.  Once the house has passed the legislation, Gov. Chris Gregoire would have five business days to sign it into law, which she has indicated she will do.  Opponents wishing to challenge the new law would have until June to collect 120,557 valid signatures – the amount required to place a referendum on the November 2012 ballot.