A commissioner fills out a marriage certificate as gay weddings resume at City Hall in San Francisco over the weekend. (AP Photo/Marcio Jose Sanchez)

Now that the gay marriage fight is intensifying on the state level, how much will both sides spend on it over the next three years? Tens of millions of dollars.

An array of groups has already mapped out plans to raise and spend millions between now and the end of 2016. Here is a look at some — but not all -- of the key players:

Freedom to Marry. Since 2012, Freedom to Marry has invested $5.8 million through its Win More States Fund directly into state campaigns, and leveraged another $2.4 million from other groups. Marc Solomon, the group’s national campaign director, said that the group aims to “raise at least $20 million between now and the end of 2016 to win more states and in order to finish the job and get back to court as quickly as possible.” Even in states where there is not a current ballot initiative underway, such as New Mexico, Freedom to Marry is spending money on a public outreach effort along with major Hispanic groups such as National Council of La Raza and the Mexican American Legal Defense and Education Fund to sway Latino voters. The campaign, called “Famila es Famila,” includes paid advertising as well as online and social media efforts.

American Civil Liberties Union. While the ACLU has spent years mounting legal challenges to expand the definition of marriage, it is ramping up its state legislative advocacy efforts in the wake of the Supreme Court’s recent decisions on the Defense of Marriage Act and Proposition 8. It currently has $2.4 million in 501(c)(4) funds it can spend this year on the new campaign, according to executive director Anthony Romero, “but we are clearly going to need more.” The group is soliciting donations from more than a dozen large philanthropists, Romero said, and is “also launching a micro-donations campaign designed by Purpose, a social networking and marketing firm.”

Human Rights Campaign. While HRC would not disclose its future fundraising targets, it spent nearly $5.2 million on campaigns in the four states that had 2012 ballot initiatives on same-sex marriage: Maine, Maryland, Minnesota and Washington.

HRC spokesman Michael Cole-Schwartz said the group's 1.5 million members would be willing to fund future efforts to expand gay marriage given that there is a "sort of two Americas that are emerging, states with marriage equality and then these states where there’s virtually nothing."

"There are a lot of people who are interested in keeping the momentum going," he added.

While same-sex marriage activists have outspent their opponents recently—proponents spent nearly $33.9 million on the four state ballot initiatives in 2012, compared to the $12 million on the other side—conservatives said they are now mobilized to invest in these state-level fights.

National Organization for Marriage.  Communications Director Thomas Peters said NOM pledges "to raise as much as it takes to defend marriage nationwide and hold lawmakers and Congress accountable." NOM remains one of the biggest funders of efforts to define marriage as between a man and a woman. The group -- along with the Catholic Church and its affiliate the Knights of Columbus -- accounted for nearly two-thirds of conservatives’ spending on the four same-sex marriage ballot initiatives last year.

Faith & Freedom Coalition. Ralph Reed, who heads the coalition, said his group is already reaching out to donors to see how much they will pour into states such as New Jersey and Iowa. “Funds have never been offered,” Reed said. “I don’t think money will be a problem.”