The referendum on marriage equality in Ireland set for Friday has ardent proponents on both sides, but is American money involved as well?

The influential National Organization for Marriage (NOM), based in Washington, D.C., says it fully supports a no vote, but denies funding the no campaign in Ireland. Irish law says that foreign donations are prohibited for referendum votes.

NOM, according to a report in The Guardian, has been encouraging its supporters to visit, which is urging Irish citizens to keep marriage law as is.

“Just like in campaigns for marriage here in America,” a NOM letter says, “slanted public opinion polls become fodder to influence and depress supporters of marriage. This is happening in Ireland. If [the no campaign] can manage to pull off a victory, it will be a tremendous boost to the cause of marriage worldwide. Please do what you can to bring awareness to their efforts.”

Backers of a no vote are stepping up their efforts in the days ahead, with ads booked in the various county newspapers, and Catholic bishops releasing letters asking parishioners to vote no.

The no campaign alleges that groups affiliated with the yes campaign have received significant financial support from Atlantic Philanthropies, the group established by Irish American billionaire Chuck Feeney who aims to give away all of his fortune.

The organization declined to discuss its role in the referendum, but backers of a yes vote say they’ve received no money from the U.S.

“Atlantic Philanthropies are not funding the Yes Equality referendum campaign. Yes Equality is fully funded through its supporters organizing fundraising initiatives throughout Ireland,” Brian Sheehan, the co-director of pro-gay marriage group Yes Equality, told “The Guardian.”

“In addition we ran a crowd-funding campaign to raise monies for our poster, bus tour and booklet campaigns. All elements of the Yes Equality campaign are appropriately registered with the Standards in Public Office commission. Yes Equality is entirely dependent on generous small donations from around the country. The average donation made to Yes Equality has been €70.”

Irish writer John Waters, a backer of the group First Families First which is anti-gay marriage, says Atlantic Philanthropies has been “allowed to swamp the Irish democratic process.”

In the past Feeney’s group has supported Amnesty International in Ireland and the Gay and Lesbian Network, both of which support a yes vote. 

Recent opinion polls show a solid lead for the yes campaign, with 58 percent of those polled by “The Irish Times” last week stating that they would vote yes.