The difficulties, in pivotal battleground states including Wisconsin and Nevada, come as the group, America PAC, races to enlist voters behind the Republican candidate in the final two weeks before the Nov. 5 election. Four people involved in the group's outreach told Reuters that managers warned canvassers they are missing targets and needed to raise the number of would-be voters they contact.

Alysia McMillan, who canvassed for the PAC in Wisconsin, said field organizers recently told campaigners there they weren't reaching daily objectives and were on track to miss an ultimate goal of contacting 450,000 voters by Election Day. In one meeting with canvassers, recorded by McMillan and reviewed by Reuters, a manager warned of the shortfall.

"We're not going to hit 450,000, not with what we've got now," the manager said in the Oct. 8 meeting. It isn't clear how many knocks the Wisconsin teams have reached so far.

McMillan, who worked for two local contractors hired by America PAC to knock on voter doors, said she is speaking out because she is concerned a shortfall could cost the former president a victory. "If this isn't looked into in a timely manner, this can result in a waste of time and money and risk President Trump winning the election," she told Reuters.

McMillan said she was fired by one contractor, after a pay dispute, but was hired by another shortly afterward.

One canvassing manager in Arizona said leaders there had issued similar warnings. Three other people familiar with the outreach told Reuters that Chris Young, a Musk aide and longtime Republican operative, had recently traveled to Nevada to audit whether doorknocking tallies there had been inflated by some of the workers hired by contractors. Another person briefed on the matter said America PAC was struggling to find sufficient people to conduct audits in other states.

A person close to America PAC's operations said McMillan's account of a Wisconsin shortfall is inaccurate and that the group will reach its goals. Senior operatives, the person added, routinely visit field offices to check on performance.

Young didn't respond to a request for comment.

America PAC's ongoing outreach is built around door-to-door efforts to convince "low propensity voters" – those who may support Trump, but could stay home instead of voting – to cast their ballots. The work has focused on battleground states, where any small difference in voter turnout could clinch victory for Trump or Vice President Kamala Harris, the Democratic candidate, in an election that polls continue to say is too close to call.

Musk, ranked by Forbes as the world's richest person, so far has supplied at least $75 million to America PAC, according to federal disclosures, making the group a crucial part of Trump's bid to regain the White House. The entrepreneur behind carmaker Tesla and rocket and satellite venture SpaceX has increasingly supported Republican causes. This year, the mogul became an outspoken supporter of Trump, who has said if elected he would appoint Musk to head a government efficiency commission.

Musk didn't respond to a request for comment.

A Trump campaign spokesperson declined to comment.

Despite the influx of cash, some of America PAC's outreach has been plagued by disarray, the people familiar with its efforts told Reuters. As with many campaign operations, the group has hired contractors to carry out grass-roots efforts, relying on hourly workers to knock on doors and speak face-to-face with potential voters.

Some of those workers have been difficult to retain. Three canvassers, who asked not to be identified, told Reuters the work isn't worth the pay, starting at some contractors at as low as $20 per hour. In some cases, they added, canvassers drive long distances in remote areas and don't get reimbursed for gasoline.

In Nevada, it isn't clear whether Young's audit has concluded, reached any findings or prompted any change in America PAC's outreach. Text messages reviewed by Reuters show managers at one Nevada contractor, Lone Mountain Strategies, fretting because they had to fire canvassers who used smartphone apps to disguise their locations and lie about their doorknocking numbers.

"Our auditors keep catching people cheating," one of the messages read. "We've fired two people today and auditors are going around checking doors for flyers."

Lone Mountain Strategies didn't respond to emails or phone calls seeking comment.

America PAC recently updated its website to prominently display advertisements seeking canvassers. "Pay starts at $30 per hour, with bonuses for performance," the site reads.