PORTLAND, Maine — A co-founder of Facebook and the editor-in-chief of liberal magazine The New Republic has offered a $100,000 matching gift to the campaign supporting same-sex marriage.

Mainers United for Marriage on Monday announced the fundraising challenge from Chris Hughes and his fiance, Sean Eldrige, president of Hudson River Ventures and senior adviser to Freedom to Marry. The campaign will have until June 7 to raise the matching funds.

“Voters in Maine have a historic opportunity to win marriage at the ballot [box] in November,” Eldridge said in a press release issued by the Maine campaign. “We are encouraged by strong statewide support for the initiative and the top-notch campaign team that’s in place, and we hope that our support will motivate others to invest in the campaign. With numerous marriage equality cases heading to the Supreme Court, there is nothing more important than growing momentum and winning the freedom to marry in more states.”

Fundraising efforts will include direct mail and email solicitations, phone calls and the use of social media, David Farmer, spokesman for the campaign, said Monday.

Mainers United for Marriage will have four weeks to raise the matching fund and have set a goal of raising $25,000 per week, according to the press release. The gift is being made through Freedom to Marry’s Win More States Fund.

“Supporters of marriage in Maine have a chance to double the impact of their contributions,”Matt McTighe, the campaign manager for Mainers United for Marriage, said in the press release. “We can win in November, but we need help to continue the conversations we’re having with voters. This matching gift challenge is critical to raising the early resources we need for our campaign. Sean and Chris are strong advocates for the freedom to marry, and our campaign greatly appreciates this early support.”

Mainers United for Marriage is leading the campaign for a yes vote on a November citizen’s initiative that would allow same-sex couples to receive a marriage license while also protecting religious freedom.