Today lawmakers in the only US state to allow gay marriage will consider whether to call a referendum on changing the state constitutuion to ban it.

Activists from both sides of the argument spent most of yesterday engaged in furious lobbying of members of the state legislature.

A referendum of all Massachusetts voters on a change to the state’s constitution needs the backing of a quarter of state lawmakers, in two successive sittings.

On the last day of session of the old state legislature in January, the measure won approval.

Now the new legislature, elected in November 2006, will be asked to vote on the proposal.

The decision to grant same-sex marriage in the state was made by a court in 2003, and there have been calls for a referendum on the issue ever since.

Over 8,000 same-sex couples have been married since the state made such unions legal.

Governor Deval Patrick, who marched in Boston’s Gay Pride parade last weekend, is trying to persuade members of the legislature to vote down the proposed referendum.

Patrick was be sworn in as governor of the Commonwealth of Massachusetts in January, the first African-American to hold that office.

The intense lobbying for voters, both for and against, is causing some lawmakers to consider changing sides.

Republican state senator Robert L. Hedlund, said after a meeting with the Governor:

“I’m going to take one more night to sleep on it. Personally, I’m not threatened by same-sex marriage, but obviously there’s a lot of people that feel strongly based on the volume of input I’ve had.”

Gay marriage advocates are quietly confident that the referendum proposal will be voted down, but with only eight votes between victory and defeat, every incident has major significance.

The hospitalisation of a pro-referendum state legislator has been endlessly discussed, with commentators wondering if he will be well enough to vote today, and if he will change his mind.

Amendment supporters have collected 120,000 signatures opposing gay marriage.

If passed, the ballot measure would seek to define marriage as only between a man and a women, stopping any future gay weddings, though any gay or lesbian wedding ceremonies carried out up to and until the ballot would be legally valid.