The front-runner to be Britain's next prime minister, Boris Johnson, came under renewed pressure on Sunday over a late night row with his girlfriend and fresh links to former Trump aide Steve Bannon.

Polls conducted for the Mail on Sunday newspaper before and after Britain's front pages were dominated by the domestic argument showed that Johnson's lead over rival Jeremy Hunt, the foreign secretary, had evaporated amongst all voters and had narrowed among supporters of his ruling Conservative Party.

Johnson declined to answer questions about the incident at a hustings for party members on Saturday, saying to applause that the audience wanted instead to hear about his plans for Britain three years after the country voted to leave the European Union.

Hunt, who was campaigning in Scotland on Sunday, told Sky News that Johnson, a former foreign secretary and former London mayor, "needs to show he's prepared to answer difficult questions."

"I think someone who wants to be prime minister should answer questions on everything," he said.

Hunt said he was not going to comment on Johnson's private life. "That's for others to make their judgments on," he said. But he added that Johnson had to engage more in the leadership race, including taking part in more TV debates.

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The clear favorite, Johnson had tried to stay out of the limelight during the campaign, and opponents have accused him of running from scrutiny to avoid the gaffes that have been a feature of his career so far.

However, police were called to an address in south London where Johnson is living with girlfriend Carrie Symonds in the early hours of Friday after neighbors heard a loud altercation.

Polling for the Mail on Sunday showed Johnson was seen as the best prime minister by 36 percent of all voters on Thursday, while Hunt was supported by 28 percent. But Johnson had lost the lead on Saturday, with 32 percent supporting Hunt and 29 percent Johnson.

Among Conservative voters, Johnson's lead fell from 55 percent to 45 percent, while Hunt's standing rose from 28 percent to 34 percent, the polls conducted by Survation showed.

Johnson also came under scrutiny on Sunday for his relationship with Steve Bannon, the controversial former adviser to U.S. President Donald Trump.

Footage published by the Observer showed Bannon claiming that he had helped craft Johnson's resignation speech as foreign secretary last year.

The pair got to know each other professionally when both were in office, and were reported to have met again in an unofficial capacity last summer.

Johnson said at the time that "the so-called relationship" with Bannon was a "lefty delusion" and his office dismissed the latest claims of a working relationship as "totally preposterous to the point of a conspiracy."