Liberal Democrat leader Nick Clegg was facing mounting pressure over tuition fees today amid more signs of splits among his MPs.
Transport Minister Norman Baker hinted that he could choose to resign from the government rather than back sharp hikes, while backbenchers urged the postponement of Thursday's crunch vote.
Meanwhile, the situation descended into confusion after an impostor pretending to be Lib Dem ministerial aide Mike Crockart said he was also ready to quit over the issue.
Deputy Prime Minister Mr Clegg is due to make a last-ditch effort to head off a crisis when he addresses his parliamentary party tomorrow night.
Lib Dem grandee Lord Ashdown has also appealed for MPs not to breach the coalition agreement by voting against the plans, while Downing Street warned that the principle of collective responsibility for ministers still applied.
However, there were signs that opposition within the party was hardening despite efforts to strike a deal.
Asked on BBC One South East's Politics Show whether he would be backing the change or abstaining, Mr Baker said: "Or voting against. There are three options and, to be honest with you, I genuinely haven't decided."
He added: "It's an option if you resign. There are three options on the table and I haven't yet decided what I'm going to do."
In a bizarre episode, someone claiming to be Mr Crockart, the parliamentary private secretary to Scottish Secretary Michael Moore, told the Evening Standard: "I will be voting against 100%. I'm not going to be pushed out. Resigning probably will be the only option."
Questions were only raised about his identity when the impersonator was interviewed on BBC Radio 4's the World at One, and colleagues realised it was not the Edinburgh West MP.
The Lib Dems released a more tempered statement on behalf of the real Mr Crockart that said: "Discussions are still going on with parliamentary colleagues.
"I have not made a final decision."