Birmingham MP Lynne Jones has been approached by Liberal Democrats urging her to defect to their party.
The Labour MP, who is to stand down at the next election, revealed she had been approached in the House of Commons lobby, where MPs go to vote. But she had turned the offers down, insisting she could not betray the Labour activists in her Selly Oak constituency.
Dr Jones, an MP for 15 years, has announced she will not stand again at the next election because she is "weary" of fighting against the Labour leadership. She has opposed the Government on issues such as involving the private sector in the NHS and education, and over the war in Iraq.
The MP has set out her reasons for quitting in The House magazine, Parliament's own in-house journal which is edited by Birmingham MP Gisela Stuart (Lab Edgbaston).
She said: "Being typecast as a rebel was never what I wanted, but the inevitable consequence of short-sighted policies like cutting lone parent benefits to save #65 million on a budget that ended up #1 billion underspent or, worse still, following Bush to war in Iraq."
She added: "Despite efforts to woo me away, I still feel that the Labour Party is the only party that can achieve the fairer and more equal society that I long for."
Dr Jones said she had been approached by Liberal Democrats in the House of Commons, while supporters in Birmingham had suggested she stand again as an independent or a candidate for Respect, the left-wing party best known for its opposition to the war.