At least five top advisers to former Minnesota governor Tim Pawlenty have been working for little or no pay for several months, a campaign source said Wednesday.

The news establishes with more certainty the emerging portrait of Pawlenty as struggling to keep up with the larger and better-funded operation of his main rival for the Republican presidential nomination, former Massachusetts governor Mitt Romney.

It also raises the question of whether Pawlenty will have the necessary resources to compete in a long, state-by-state campaign against Romney as well as other GOP candidates who have better-established fundraising networks, including former Utah governor Jon Huntsman Jr. and U.S. Rep. Michele Bachmann (Minn.).

While some staffers are temporarily forgoing a larger paycheck, others signed up with the understanding that they would volunteer their time for the long term, said the Pawlenty aide, who spoke on the condition of anonymity to discuss internal personnel matters. The disclosure, which will appear in financial reports that will be made public next month, does not suggest any sudden problems with the campaign, he said.

“This isn’t ‘We’re broke and we can’t afford to pay you,’ ” the aide said. “We’re raising exactly what we said we were going to raise. We’re paying our consultants exactly what they expected to be paid right now.”

Pawlenty spokesman Alex Conant declined to comment on staff pay. But he said the campaign is well-positioned to compete. “We are confident that we will raise the resources necessary to execute our strategy and win the nomination,” he said.

The source said those on Pawlenty’s team working for little or no pay include the top two strategists, Phil Musser and Jon Lerner, as well as advisers Sara Taylor Fagen, Terry Nelson and Brian Hook. The advisers are earning in the range of zero to $1,000 a month, plus reimbursements for expenses, he said.

The source said next month’s reports will show that the campaign has experienced some ups and downs in its fundraising efforts — including a dip after Pawlenty’s widely panned performance in last week’s debate.

Romney, in his second run for president, is expected to log an even more impressive report than he did for the comparable period in the 2008 cycle, when he raised $21 million.

Bachmann is also likely to report a sizable haul, in part because she can transfer money from her congressional fundraising committee. She has outraised nearly all other members of Congress over the past several years.

This isn’t the first time campaign staffers have gone without pay. In the summer of 2007, Sen. John McCain (R-Ariz.) lost his strategist, John Weaver; his campaign manager, Terry Nelson; and well over half his 120-member team after heavy spending and inadequate fundraising left the account dry.

The Pawlenty source noted that several of the consultants working for little or no pay have given the campaign $2,500 donations, the maximum allowed under federal law. It’s another sign, the source said, of the team’s commitment.

“Our consultants are either volunteering their time or working for peanuts,” he said. “This may be hard for some in Washington to accept, but they’re on Team Pawlenty for the right reasons — they believe in the candidate and cause.”