LONDON, July 6 (Reuters) - Britain's Boris Johnson defied pressure from senior ministers and a mounting rebellion within his party to quit on Wednesday (Jul 6), vowing to stay on as prime minister and fight off any attempts to oust him.

After more than 30 resignations from within the government and with many lawmakers in his Conservative Party in open revolt, some cabinet ministers went to Downing Street to tell Johnson he needed to go, a source said.

One encouraged him to make a dignified exit by setting his own timetable rather than face a confidence vote.

But despite the clamour for him to resign, Johnson was continuing to focus on the important issues, a government source said after his meeting with members of his top cabinet team. A senior Conservative said the prime minister was digging in.

"I am not going to step down and the last thing this country needs, frankly, is an election," he told a parliamentary committee earlier, saying he had a mandate from the 2019 national election, which he won with a large majority.

Johnson also refused to say if he would try to stay in the job even if he lost a confidence vote from his own lawmakers. That could come next week if they agree to change the party's rules, which only allow one such challenge a year. He narrowly won a similar vote last month.

"The prime minister is deluded if he feels he can cling on in the face of collapsed parliamentary support," said a senior Conservative lawmaker on condition of anonymity. "He is embarrassing the Conservative Party and showing contempt for the electorate."

But culture minister Nadine Dories said she was behind Johnson and, when asked if others also still backed him, she replied: "Yes, definitely."

The dramatic resignations on Tuesday of his health and finance ministers triggered a growing swell of other ministerial departures, while many Conservative lawmakers openly said they wanted him gone, questioning his fitness to govern and his integrity.

At parliamentary questions on Wednesday some Conservatives struggled not to laugh when others poked fun at him and he took a pummelling from a committee of senior politicians over his past behaviour, his motivation and some of the scandals that have come to define much of his tenure.