The lead group that tried unsuccessfully to block same-sex marriage in Minnesota unveiled a new effort Thursday to become a powerful force in legislative races and defeat state House candidates who oppose their views on marriage.

"The majority of Minnesotans support marriage between one man and one woman, and they deserve a majority of representatives in their government who do as well," said John Helmberger, chairman of Minnesota for Marriage and CEO of Minnesota Family Council, a nonprofit Christian group.

The formation of the new political group, the Marriage Majority Initiative, comes the day that Minnesota joined 12 other states in legalizing same-sex marriage. Aided by a handful of Republicans in both chambers, the DFL-controlled Legislature passed the measure to legalize same-sex marriage earlier this year. DFL Gov. Mark Dayton signed the bill May 14.

Marriage Majority founders are not sure they will be able to overturn the legalization of same-sex marriage anytime soon, but they are focused on helping supporters "find better representation in the Legislature," said Autumn Leva, a spokeswoman.

The new group has national firepower. Brian Brown, president of the National Organization for Marriage, will serve as the Marriage Majority Initiative's treasurer.

The national group renewed its pledge of $500,000 to defeat any Republican legislators who opposed their stance on marriage or aid Democrats who sided with them. The group is taking a similar role in Rhode Island, which also legalized marriage Thursday.

"This is a sad day in Minnesota and Rhode Island as politicians have allowed a mockery to be made of the institution of marriage," said Brian Brown, NOM's president. "We will work tirelessly to hold the politicians accountable for this travesty."

Marriage Majority Initiative will consider weighing in on state Senate races when those seats are up for election in 2016.

Minnesotans United, the group that pressed for passage of same-sex marriage, has created a separate political action group that is already aggressively raising money to fend off challengers for legislators in vulnerable districts who took difficult votes to support same-sex marriage.

Minnesotans United's political group "will work tirelessly to ensure that the leaders in the Legislature – Republican and Democrat – who voted yes for marriage this year have the grassroots and financial support they need to be re-elected," campaign manager Richard Carlbom said earlier.