The state of Maryland, which just two weeks ago looked set to become the first US state to legalise same-sex marriage by referendum, is now deadlocked on the issue, polls indicate.

Earlier in the month, A poll released suggested that voters in the state would be the first to approve equal marriage by a popular vote.

Reports have suggested that part of the reason for the change was that some black pastors in the state had been urging voters to vote against equal marriage at the referendum on 6 November, the LA Times reported.

Since the previous poll, voters have also been targeted by TV, radio and newspaper ads both supporting and opposing the idea of upholding Maryland’s equal marriage law.

Polls by the Baltimore Sun seemed to suggest that the support of African American voters had fallen from 50% to 42%, and opposition had risen from 25% to 50%, from before, to after the surge in TV advertising.

Earlier in the month, Harold L Dugger of the First Baptist Church, Prince George’s County, said his congregation should vote against the measure to legalise equal marriage:

“No vote means you’ve already voted,” He told his churchgoers. “We stand firmly on the word of God — your faith has to do a lot with what you do at the polls.”

Kevin Nix, a spokesperson for Marylanders for Marriage Equality, said that the advocates of equal marriage know that the polls can be wrong, and that in other states where the polls said equal marriage had good support, it was still defeated at the ballots:

“We know from the history of this issue in other states that the polls are not always right,” he said.

Support for equal marriage in Maryland in the past month has come from various places, some unexpected.

A Baltimore priest who had served his parish for almost forty years, spoke out yesterday in an impassioned sermon urging Catholics to vote in favour of equal marriage.

The National Association for the Advancement of Coloured People in Maryland launched a series of radio adverts in early October, urging voters to support equal marriage. 

Today, Brad Pitt agreed to donate $100,000 (£62,000) to help the Human Rights Campaign raise money for its efforts to support equal marriage initiatives in several US states, including Maryland.

New York Mayor Michael Bloomberg also donated $250,000 (£155,000) to the pro-marriage equality campaign in the state.

On 6 November, Maryland, as well as Washington and Maine voters will decide whether or not to legalise equal marriage in those states. Minnesota voters will also choose whether to make a constitutional amendment which would define marriage as only between one man and one woman.