A YEAR AGO, LGBT advocacy group Basic Rights Oregon (BRO) took a look at their numbers and made a hard choice: They would be waiting for marriage.

The state's pro-gay politicos decided to hold off until at least 2014 to push a constitutional amendment legalizing same-sex marriage, even though that meant depriving the state's nearly 15,000 same-sex couples the full rights of citizenship for two more years.

Looking now at the extremely close and expensive race over Washington's Referendum 74, it seems like BRO made the right choice. If Washington voters uphold the same-sex marriage law passed by their legislature in February, it will be by a hair: The latest Elway Poll shows the referendum ahead 49 percent to 45 percent, with a sliver of undecided voters who will likely fall into the "no" camp.

When it crunched the numbers a year ago, BRO found that only 48 percent of Oregon voters supported same-sex marriage (which would have to be legalized via a statewide constitutional amendment, thanks to a 2004 measure). They wanted larger support before launching and worried about raising what they estimated would be $10 million for the fight.

"I still feel absolutely confident in the decision we made to build an education campaign over the next two years," says BRO Executive Director Jeana Frazzini. "There are four states where marriage is on the ballot and only in one of those places are we on the ballot on purpose—Maine."

Just as BRO thought, the Washington campaign has required a mountain of money. Six pro-marriage political action committees have raised $13.3 million, pulling big-business donors (like Bill Gates, Nike, and chief executives at Starbucks, Alaska Airlines, and Microsoft) and small donors from all over the country. Fifteen percent of donations for the main pro-same-sex marriage group, Washington United for Marriage, have come from out of state.

The anti-marriage side, meanwhile, has $2.27 million in its war chest. Of that, $1.49 million comes from just three sources: conservative Seattleite Thomas Matthews, the Catholic Knights of Columbus, and the National Organization for Marriage. Overall, the anti-marriage campaign has received just 5,025 donations compared to the pro-gay groups' 22,000.

Referendum 74 spokesman Zach Silk says the race would be close even if the issue hit the ballot in two years, but that there's good momentum from the legislature, Washington's governor, and President Barack Obama coming out to support the law. Washington is better positioned than Oregon for voting on same-sex marriage now, Silk says, because it has a more urban population and deeper pockets.

"You're fighting for social change—that doesn't come easy," says Silk. "If we win, we'll be glad we went. If we lose narrowly, we'll have moved the needle significantly."

For the past six weeks, BRO has turned its volunteer force over to the Referendum 74 campaign, filling 100 canvassing and phone banking shifts a week. No matter which way Washington votes, Oregon will continue to keep its eyes on 2014.