Maine became the fifth state to authorize same-sex marriages, the second to do so with legislation, and the fourth to do so in New England.

Of the six states in the region, Massachusetts, Connecticut and Vermont already recognize gay marriage, and the two that don’t—New Hampshire and Rhode Island—are moving rapidly in that direction. New Hampshire is expected to authorize same-sex marriage before the end of the month.

Maine’s Democratic Gov. John Baldacci signed the bill into law despite previously stating his opposition to gay marriage. In a statement, he explained his change of heart: “I have come to believe that this is a question of fairness and of equal protection under the law, and that a civil union is not equal to civil marriage.”

The New England action comes on the heels of Tuesday’s historic vote by the District of Columbia City Council to recognize gay marriages performed in other states—seen by many as the first step toward legalizing same-sex marriage in the nation’s capital. Once the bill is signed by Mayor Adrian Fenty, as expected, it will go before Congress, which has 30 days to review the bill. If Congress doesn’t act within 30 days, the bill becomes law automatically.

But all is not well.

Maine officials say gay marriage opponents are challenging a new law allowing same-sex couples to wed.

Secretary of State Matthew Dunlap said Thursday that opponents filed a challenge under the state’s “people’s veto” provision.

It allows for a referendum to overturn laws if opponents can collect enough signatures.

In other news from the Northeast on same sex marrigae–The New Hampshire legislature has passed a same sex marriage bill.   If New Hampshire Gov. John Lynch signs the bill or lets it become law without his signature, his state would become the sixth overall to allow gay marriage and the fifth in New England.