Louisiana Democratic Senator Mary Landrieu has said that while she personally believes in marriage equality she will not support its legalisation, out of deference to her state’s anti-gay partnerships stance.

She told a CNN reporter on Friday that her own personal view was: “People should love who they love and marry who they want to marry.”

However, she added: “My state has a very strong constitutional amendment not only against gay marriage but against gay partnerships. So I’m looking at the people of Louisiana trying to represent their interests.”

She has previously said: “The people of Louisiana have made clear that marriage in our state is restricted to one man and one woman.”

Yesterday Mark Pryor, the Democratic Senator for Arkansas, said he was “undecided” on the issue, and added he had “never really thought” about whether being gay is a choice.

Along with Joe Manchin of West Virginia and Tim Johnson of South Dakota, Mrs Landrieu and Mr Pryor are the only Democratic Senators not to have backed marriage equality.

This week Democratic Senators Heidi Heitkamp and Joe Donnelly each announced their support for equal marriage via Facebook, and Timothy Kaine also shifted his position on Tuesday.

They followed Democratic Senators Mark Begich and Mark Warner, who both came out in support of same-sex marriage before the Supreme Court’s hearings on the subject, following the precedent set by Claire McCaskill. Senator McCaskill announced her support via a Tumblr post.

Earlier this week Republican Senator Mark Kirk declared his support for equal marriage, saying: “Life comes down to who you love and who loves you back – government has no place in the middle.”

Republican Senator Rob Portman announced that he  endorsed same-sex marriage on 15 March.

The announcement was particularly surprising as Mr Portman had been one of the original sponsors of DOMA. He said the coming out of his gay son had prompted him to rethink his views.