JEFFERSON CITY - Governor Jay Nixon publicly opposed gay marriages for years but said Thursday afternoon that anyone who wants to get married should be able to.

Nixon made the statement after he announced he will issue an executive order to the Missouri Department of Revenue to "accept the jointly-filed state tax returns of all legally married couples, including same-sex couples legally married in other states." In his 2008 and 2012 campaigns, Nixon opposed gay marriage.

"I just don't think we should treat folks differently in this zone anymore," Nixon said. "I think if folks want to get married they should get married."

But shortly after the announcement, the Democratic governor faced opposition from the opposite side of the aisle.

"A couple years back I distinctly remember a constitutional amendment not recognizing same sex marriage in any way, shape or form," a Missouri GOP spokesperson, Matt Wills, said.

In 2004, Missourians voted for a constitutional amendment stating, "that to be valid and recognized in this state, a marriage shall exist only between a man and a woman."

Bryan Fischer from the American Family Association,  spoke out against the governor's decision.

"It is illegal, it is immoral, and it is unconstitutional," Fischer said. "What he has done here, he has betrayed the will of the people of Missouri."

However, the state may be changing it's previous views. In 2012, a Democratic-leaning polling firm, Public Policy Firms, found through telephone polling that "64 percent of Missouri voters believe gay couples should either be allowed to marry or form civil unions."

A few hours after the governor's announcement, House Speaker Tim Jones, R-Eureka, called on Attorney General Chris Koster to look into the legal authority of the governor to make this decision.

"This executive order is nothing but an attempt to violate the voters’ will, unlawfully ignoring a constitutional amendment to provide the Governor’s liberal allies a policy victory," Jones said.

Calls to Sen. Jolie Justus, D-Jackson County, an openly gay lawmaker, were not immediately returned. When Justus was chosen as minority leader in January of 2013, she said she did not want to push the issue of gay marriage because it was not the will of the people of Missouri. She said she was more focused on making sure people have basic human rights protections.

A.J. Bockelman, the executive director of PROMO, an organization promoting equality for LGBT individuals in Missouri, said there was some cause for celebration, but cautioned that gay individuals could still be fired or denied housing because of their sexual orientation.

"We don't have those basic rights yet," Bockelman said.

Bockelman said while the organization is still comitted to marriage equailty, he said the group has not decided what the best pathway for obtaining that goal is. He said a campaign for either an initiative petition process or going through the legislature to put the issue on the ballot would cost between $6 or $7 million.

"It provides guidance for same sex couples that had so far not been provided," Bockelman said.

Idaho, Kansas, North Dakota, and Virginia have decided not to accept joint-filings by same-sex couples for state taxes.