The campaign of Democratic presidential candidate Joe Biden will begin knocking on doors of prospective voters this weekend after saying for months that such action was unsafe and unnecessary during the coronavirus pandemic.

Biden’s aides have been critical of President Trump’s campaign for its use of canvassers to contact potential voters, saying Republicans were putting the health and safety of Americans at risk amid a coronavirus pandemic that has killed more than 207,000 people.

Instead, the Biden campaign has focused on connecting with voters virtually, touting the metric of “meaningful conversations” — of which they say they had 5.9 million during September — rather than on the numbers of doors knocked.

But with five weeks to go before Election Day, and with ballots already being cast in many states, the Biden campaign said it decided to expand into in-person canvassing, largely focused around its get-out-the-vote operation. The move comes after Republicans have built a far bigger in-person political operation during the pandemic, knocking on 19 million doors.

“Our volunteers are fired up and have exceeded every goal we’ve set,” Biden campaign manager Jen O’Malley Dillon said Thursday. “We’re now expanding on our strategy in a targeted way that puts the safety of communities first and foremost and helps us mobilize voters who are harder to reach by phone now that we’re in the final stretch and now that Americans are fully dialed-in and ready to make their voices heard.”

Republicans have built a substantial political apparatus in battleground states even as Democrats have avoided activities such as door-knocking and have not opened in-person offices. Republican officials — along with some Democrats privately — say those efforts could make a difference in driving up Republican turnout in key battleground states even as Trump lags Biden in the national and key state polls.

“First the Biden campaign said door knocking endangered people’s lives. Then just a couple of weeks ago, they said door knocking didn’t have any impact in elections,” said Trump campaign spokesman Tim Murtaugh. “What changed? They know they’re being hopelessly outworked on the ground and down-ballot Democrats in key states have been freaking out about it.”

O’Malley Dillon had previously said the campaign was not knocking doors because it wasn’t needed and it was no longer the “gold standard,” as the campaign focused on Trump’s coronavirus response. Last month, the Biden campaign attacked Trump and his team for showing up on voters’ doorsteps and said it had knocked on zero doors because it was not safe and prospective voters did not want visitors.

“Donald Trump’s voter outreach fails to understand the concerns of Americans right now,” the Biden campaign’s states director, Jenn Ridder, told The Washington Post last month. “He is blatantly having events. He is blatantly going to doors. And the reality of this country is, they are worried about the economy, they are worried about sending their kids to school, and they are worried about covid-19.”

This weekend, several hundred Biden canvassers will be going out in Nevada, Michigan, New Hampshire and Pennsylvania. A Biden campaign adviser said 6,000 people had shown interest in knocking on doors in Pennsylvania.

Republican Party officials say their volunteers have knocked on the doors of 19 million voters they believe are likely Trump voters, either talking to the resident or leaving a piece of literature if no one answered. Mike Reed, a Republican Party spokesman, said Trump volunteers knocked on two million doors this week and will ramp up their efforts in the coming weeks.

Republicans have also opened about 300 offices across the country. They have held thousands of in-person events, including 847 debate watch parties Tuesday night.

These efforts as well as rallies held by Trump have been heavily criticized by Democrats and public health officials who have warned they have the potential to spread the virus and cost lives.

The Trump campaign has downplayed safety concerns and with regard to door knockers, officials said the volunteers are encouraged to wear masks and stand several feet away from residents.

“I find it interesting, the Democrats say, ‘there’s a pandemic, there's a pandemic, that's why we don't have a field program, that's why we haven't done anything,’ ” said Richard Walters, the RNC chief of staff. “What did they do from January 2019 until March of this year? They didn’t have a program.”

Walters and other party officials said voters were more likely to cast a ballot when actual humans contacted them. “People want to be asked for their vote,” he said. “Candidates sometimes take that for granted.”

Chris Carr, the political director of the RNC, said knocking on doors and calling voters once had a poor success rate. Since coronavirus, he said, that has changed. The RNC did not say exactly how many people had answered the door when volunteers knocked.

“Our connect rate is through the roof. They are home. They are bored. We want to see people. People are social creatures,” Carr said. “We are finding that people really want to talk.”

Carr said their team modeled the GOP efforts off the program run by former president Barack Obama’s campaigns. Team members were asked to read a book titled “Groundbreakers: How Obama’s 2.2 Million Volunteers Transformed Campaigning in America,” according to Carr.

“We followed their model,” Carr said. “I give them credit. Barack Obama had a movement. We have a movement under Donald J. Trump.”

Whether such efforts can buoy the Trump’s fortunes remain unclear. Voters have overwhelmingly disapproved of his response to the coronavirus.

The Biden campaign since the convention had been piloting and building a strategy to phase-in the in-person campaign activity, according to a campaign official who spoke on the condition of anonymity to describe the planning.

It has opened facililites across battleground states to distribute supplies and materials to volunteers — the campaign has 109 offices across 17 battleground states now, and intend to expand to 188 offices. There is literature with personalized notes that will be dropped off at homes — something that has already started in Pennsylvania and Nevada and will soon expand elsewhere.

Biden officials are sending volunteers to early voting locations in Pennsylvania and Virginia, and setting up tables to register voters in Florida and Michigan. Some activists in states, such as Wisconsin, have complained that the Biden campaign has been too slow to distribute signs.

Republican officials say top states for their voter interactions are Florida, Ohio, Wisconsin and Pennsylvania.

The Biden campaign intends to train volunteers on covid-19 safety measures, and they will complete a questionnaire about any symptoms and have their temperatures taken before participating in campaign activities. They will also be provided with personal protection equipment.

Before a volunteer enters a neighborhood, the Biden campaign will send out texts so that voters they are targeting know to expect a knock on the door.

The increase in the in-person canvassing coincides with more public campaign activities from Biden and his running mate, Sen. Kamala D. Harris (D-Calif.), as well as Biden’s wife Jill and Doug Emhoff, who is Harris’ husband, who participated in a yard sign parade in New Hampshire.