LONDON — Londoners responding to a knock on their front doors in recent days may have been surprised to see a familiar face grinning back at them: Hugh Grant, one of the country’s most recognizable actors, who made his mark as the floppy-haired, bumbling leading man in romantic comedies.
But Mr. Grant, who famously played a prime minister going door to door in “Love Actually,” was not looking for a lost love this time. He was looking for votes.
Celebrities have long waded into the political arena, throwing the weight of their public personas behind candidates and causes. But Mr. Grant has become one of the most vocal and active ahead of Britain’s general election on Dec. 12, pounding the pavement with candidates who differ ideologically but agree that Britain should remain in the European Union.
He has campaigned with candidates for Parliament in at least four different London-area constituencies, and he has been spotted on the city’s Underground trains, headed to and from political events.
In a climate where anger and exhaustion over the still-unresolved issue of Brexit have left Britain divided like never before, the reception for Mr. Grant’s efforts has been mixed.
Rather than campaigning for one particular party, he is instead calling for strategic voting to block the Conservative Party of Prime Minister Boris Johnson from winning a majority, backing the candidate in each race who he believes has the best chance to beat the Conservatives.
Mr. Grant is not the first celebrity to call for an end to Mr. Johnson’s time in office, but he has been one of the most prominent — and possibly the busiest — in the weeks of canvassing before the election.
This week, he was campaigning alongside Dominic Grieve, a former Conservative lawmaker who refused to support Mr. Johnson’s Brexit plans, was expelled from the party, and is now running for his seat as an independent. In a campaign video for Mr. Grieve, Mr. Grant detailed his reasons for supporting him.
“I, for the first time in my life, am getting active politically, because I think that the country is on the edge of a true abyss,” leaving the European Union without a trade agreement, he said. He described what he said would be “the catastrophe of a no-deal Brexit” under Mr. Johnson.
Speaking with voters on Monday as he canvassed with Chuka Umunna, an incumbent Liberal Democrat, he offered the same message: That the only way to avoid a disastrous withdrawal from the bloc is to edge out Conservative candidates.
“I’m wandering around London and the suburbs, banging the drum about tactical voting, because I think in the absence of complete Remain alliance, that’s our only hope as voters,” he said.
This week, he was in Chingford, northeast of London, campaigning with Faiza Shaheen, a Labour candidate, at a subway station, where he handed out leaflets and spoke with voters.
While some have applauded his advocacy, others have criticized the actor for an approach that focuses only on one issue: Brexit. And some saw his decision to campaign with both Ms. Berger and Labour candidates as hypocritical, and heckled him as he canvassed with Ms. Shaheen.
He is also using his following of nearly half a million on Twitter to push for voters to lend their support to candidates calling for Britain to remain part of the European Union.
His brash approach on social media has drawn attention since August, when his expletive-laden Twitter post, bashing a controversial Brexit maneuver by Mr. Johnson, drew hundreds of thousands of reactions.
But Mr. Grant has also received a fair share of online abuse as a result of his activism. In response to the backlash he has received since he began canvassing, some of which made mention of a past arrest for soliciting a prostitute, Mr. Grant made the unusual decision to post his infamous 1995 mugshot on Twitter account on Thursday night.
“To my dear trolls,” he wrote. “Hope this is helpful.”
But he is not alone in using his platform as an advocate for candidates. Liam Gallagher, the former Oasis frontman, told British news outlets he would be voting for the Green Party to promote climate justice.
Rob Delaney, an American comedian, has been outspoken in his backing of the Labour Party and its support for the British National Health Service. In a campaign video, he detailed his experience with the health system, describing his young son’s diagnosis and eventual death from a brain tumor, and said Labour’s commitment to preserve the service was a reason to vote for the party.
The British comedian Eddie Izzard, who has long been an outspoken Labour supporter, was again out canvassing for his party’s candidates. Lily Allen, the British singer, and Stormzy, Britain’s best-known grime artist, have also voiced support for Labour.
The American actor Danny DeVito urged fans to vote Labour at a film premiere this year, and made his support for the party clear while in London in 2017.
While the Conservatives certainly count celebrities among their fans, they have been less visible in this campaign. The party did not reply on Friday to a request for information on celebrities campaigning alongside its candidates.
But the lack of a prominent celebrity endorsement doesn’t seem to be affecting the party’s popularity. Though recent polls have shown Labour narrowing the gap, the Conservatives have consistently held a wide lead.