* PM casts himself as comic book hero, says UK leaves on Oct. 31
* Eying ballot, Liberal Democrats position as 'Stop Brexit' party
* Johnson says he wants to reach deal with EU, is making progress (Changes date, adds Liberal Democrats, Labour, background)
By David Milliken and William James
LONDON, Sept 15 (Reuters) - British Prime Minister Boris Johnson likened himself to the comic book character The Incredible Hulk in a newspaper interview where he stressed his determination to take Britain out of the European Union on Oct. 31.
The Mail on Sunday newspaper reported that Johnson said he would find a way to circumvent a recent parliament vote ordering him to delay Brexit rather than take Britain out of the EU without a transition deal.
"The madder Hulk gets, the stronger Hulk gets," Johnson was quoted as saying. "Hulk always escaped, no matter how tightly bound in he seemed to be - and that is the case for this country. We will come out on October 31."
Britain's parliament has repeatedly rejected the exit deal Johnson's predecessor Theresa May negotiated with the EU, and this month rejected leaving without a deal - angering many Britons who voted to leave the bloc more than three years ago.
Johnson wants to harness that anger to win a majority in an early national election, but his efforts to call one have so far been thwarted by opposition parties who want to first ensure Britain cannot leave the EU without a deal on Oct. 31.
The Liberal Democrats party, which has 18 seats in Britain's 650-seat parliament, on Sunday made its bid for the votes of those who want remain in the EU, toughening its anti-Brexit stance to say it would stop the exit process if it won power in an election, and would reject any Brexit deal Johnson struck.
"If people put into government as a majority government, the 'Stop Brexit' party, then stopping Brexit is exactly what people will get," party leader Jo Swinson said.
Johnson has said he wants to negotiate a new deal that does not involve a 'backstop', which would potentially tie Britain against its will to EU rules after it leaves in order to avoid checks on the border between Ireland and Northern Ireland.
The EU has so far insisted on the backstop, and Britain has not presented any detailed alternative.
Nonetheless, Johnson said he was "very confident" ahead of a meeting with European Commission President Jean-Claude Juncker on Monday.
"There's a very, very good conversation going on about how to address the issues of the Northern Irish border. A huge amount of progress is being made," Johnson told the Mail on Sunday, without giving details.
The opposition Labour Party called for more details on what Johnson was proposing.
Johnson drew parallels between Britain's situation in Brexit talks and the frustrations felt by fictional scientist Bruce Banner, who when enraged turned into the super-strong Incredible Hulk, frequently leaving behind a trail of destruction.
"Banner might be bound in manacles, but when provoked he would explode out of them," he said.
The Sunday Times reported that Johnson's senior adviser Dominic Cummings had raised the idea of suspending parliament for a second time. Parliament is currently suspended until Oct. 14 - a decision which is being challenged in the courts by those who say it is an attempt to block debate on Brexit.
STOP BREXIT PARTY
On Saturday, former Conservative minister Sam Gyimah said he was switching to the pro-EU Liberal Democrat party in protest at Johnson's Brexit policies and political style, and Swinson said she believed she could win an election.
But, polling suggests the Liberal Democrats, who in the party's modern form have never won more than 62 seats at an election, are unlikely to find themselves in a position to stop Brexit outright.
Polls published late on Saturday painted a conflicting picture of the Conservative Party's political fortunes under Johnson.
A poll conducted by Opinium for the Observer newspaper showed Conservative support rose to 37% from 35% over the past week, while Jeremy Corbyn's Labour held at 25% and Liberal Democrat support dropped to 16% from 17%. Support for Nigel Farage's Brexit Party remained at 13%.
However, a separate poll by ComRes for the Sunday Express put Conservative support at just 28%, down from 30% and only a shade ahead of Labour at 27%.
ComRes said just 12% of the more than 2,000 people it survey thought Britain's parliament could be trusted to do the right thing for the country. (Reporting by David Milliken and William James Editing by Marguerita Choy and Elaine Hardcastle)