ST. PAUL, Minn. - Six months after Minnesota voters turned back an effort to ban gay weddings, lawmakers are poised to make the state the first in the Midwest to pass a law allowing them.

The shift comes amid a rapid evolution of public opinion nationally. But with Minnesota and possibly Illinois set to broaden the definition to include same-sex couples, coastal states may soon have some company.

In November, voters unexpectedly defeated a measure that would have banned same-sex marriage in the Minnesota Constitution, even after more than two dozen states passed similar bans. That prompted gay-marriage supporters to quickly go on offense.

Those efforts culminate Thursday with a vote in the state House that Democratic leaders assured would pass. With the state Senate expected to follow suit, Democratic Gov. Mark Dayton could sign a bill as early as next week.

"We like to lead the way in Minnesota," said State Rep. Karen Clark, the Minneapolis Democrat sponsoring the bill.

In the last week, Rhode Island and Delaware became the 10th and 11th states to approve gay marriage. But so far, only legislatures in coastal or New England states have voted affirmatively for gay marriage. Except for Iowa, which allows gay marriage due to a 2009 judicial ruling, same-sex couples can't get married in flyover country.

Minnesota might go first, but Illinois could be close behind. The state Senate there voted in February to allow same-sex marriage, and supporters think they are close to securing the votes needed to get it through the House and on to Democratic Gov. Pat Quinn.

Although a few Republican politicians around the country have started to embrace gay marriage, the movement remains largely contained to states with Democrats fully in control.

Democrats control Colorado, but that state could go only as far as civil unions because of a constitutional amendment that blocks gay marriage. The same curb applies in Oregon, but a group has launched a drive to repeal the earlier ballot initiative.

Elsewhere, the political dominance of Republicans makes legalized gay marriage a difficult sell.

Last fall's defeat of the Minnesota gay-marriage ban ended a nearly decade-long push by social conservatives for stronger prohibitions on gay marriage. But the massive activist and fund-raising network built to defeat the amendment has now been harnessed to get it through the legislature.

"Our opponents did us a huge favor," said Sen. Scott Dibble, the bill's Senate sponsor. "They really accelerated the whole issue."