In the final months of President Obama’s administration, the government’s top consumer regulator was negotiating a large settlement with the student loan collector Navient, which it said had misled borrowers and made mistakes that added billions of dollars to their bills.

But after President Trump’s victory, the talks between the company and the Consumer Financial Protection Bureau broke down. Two days before his inauguration, the bureau sued Navient, accusing it of “systematically and illegally failing borrowers at every stage of repayment.” Two states, Illinois and Washington, simultaneously filed their own suits in state courts.

As the bureau has taken a softer approach toward industries, including payday lending, and had its own acting director say it too often exceeds its authority, the possibility that the Trump administration will ease up on Navient has prompted more states to join the legal fray. Five have now sued Navient, two of them within the past four months.

“There is growing concern among myself and state attorneys general that the federal government is not only losing interest in holding student loan servicers like Navient accountable, but that the federal government is actively looking for ways to shut down state enforcement actions against Navient and other student loan servicers,” said Jim Hood, the Mississippi attorney general, who sued Navient in July. “The timing of filing our lawsuit reflects that concern.”

Two years ago, Navient was willing to reach a settlement to end the bureau’s three-year investigation. It would adjust how it serviced loans and write off some private loans it owned that were considered predatory, according to three people familiar with the talks.

But after Election Day, there was a greater sense of urgency from officials at the bureau — a frequent target for criticism by Republicans. The bureau and a group of state attorneys general, who were conducting their own investigation, aimed high: fines and debt relief that together would have topped $1 billion, the people said.

The talks fell apart, prompting suits against Navient alleging that the company had harmed hundreds of thousands of borrowers by failing to steer them toward the loan repayment options that would have been best for them. Borrowers incurred nearly $4 billion in additional interest charges that could have been avoided, the plaintiffs argued in legal filings.

Among the other claims: Navient repeatedly misallocated payments and incorrectly reported to credit bureaus that some disabled borrowers — including military veterans — had defaulted when their loans had actually been forgiven.

Navient has denied any wrongdoing. “We have helped millions of borrowers enroll in income-driven repayment and successfully repay their loans,” said Nikki Lavoie, a company spokeswoman.

If Navient loses in court, the company could be required to pay billions of dollars in damages and overhaul the way it handles the accounts of some six million borrowers. A defeat could also prompt other servicers to change their policies: Navient is one of eight companies paid by the Education Department to handle the $1.4 trillion owed by 42 million federal loan borrowers.

“These problems are not just limited to Navient; these are practices we have seen at many different servicers,” said Persis Yu, the director of the National Consumer Law Center’s Student Loan Borrower Assistance Project. “It’s critical to finally have a federal agency acknowledge the problems and hold a company accountable for them.”

In public, Navient promotes its commitment to guiding borrowers. “We are here to help you successfully navigate paying your student loans,” it says on its website. But in court, Navient has said those assurances are strictly marketing hype.

“It’s friendly talk, it’s puffery, but it is not the stuff of a legal obligation to now become your financial counselor,” Navient’s lawyer told a federal judge in Pennsylvania as part of a request to dismiss the bureau’s lawsuit.

Judge Robert D. Mariani denied the request. It is reasonable for borrowers to assume that their loan servicer will act in their best interests, and Navient’s “active conduct created a duty to act in accordance with their own statements,” he wrote. Judges overseeing the Illinois and Washington cases have also rejected dismissal requests.

With the state and federal cases progressing, Navient has stepped up its efforts to personally connect with the government officials leading the enforcement efforts against it. The company has met with leaders at the federal consumer bureau, hired two former Democratic attorneys general as advisers and begun donating to networking groups that help state attorneys general raise campaign cash.

The states’ lawsuits will take on increased importance if the consumer bureau drops its case against Navient.

Such concerns were obliquely alluded to in a scathing resignation letter sent in August by the agency’s student loan ombudsman, Seth Frotman. Mr. Frotman stepped down while criticizing the bureau’s interim director, Mick Mulvaney, for putting the interests of powerful businesses ahead of consumers “harmed by the company that dominates this market.”

In an interview last month with CNBC, Mr. Mulvaney said he worried about the consequences, “from a financial standpoint and a moral standpoint,” of the growing number of student borrowers who fail to pay off their debts.

Navient has openly sought to have the bureau’s lawsuit dropped.

“There is no evidence to date to support their case,” John F. Remondi, Navient’s chief executive, told analysts on Navient’s most recent earnings call. “Our arguments here are, you’ve had five years to look for your evidence, you found none, it’s time to move on.”

Navient also made that argument privately to Mr. Mulvaney, who is also Mr. Trump’s budget director, in February in an email requesting a meeting. The email was obtained through a public records request.

Mr. Remondi called the lawsuit against his company “a prime example of what was wrong with the bureau” under Mr. Mulvaney’s predecessor. He also repeated a number of Mr. Mulvaney’s own talking points, accusing the bureau of trying “to make law through enforcement actions.”

Four months later, Mr. Remondi met with a group of the bureau’s lawyers and one of Mr. Mulvaney’s top aides, Eric Blankenstein, the political appointee in charge of the bureau’s enforcement division, who has lately faced criticism for past racial comments.

According to the two people familiar with the agency’s internal discussions, Mr. Blankenstein has particularly scrutinized the claims at the heart of the lawsuit: that Navient steered borrowers into more costly repayment options that were administratively simpler for the company.

A spokesman for the bureau declined to comment.

Navient is also ensuring that it directly reaches those who have authority to decide whether the state cases go forward.

Last year, the company retained two former attorneys general — Douglas F. Gansler of Maryland and Martha Coakley of Massachusetts, both Democrats — to help it communicate with their peers. Ms. Coakley said her Navient work was focused on helping state officials better understand the company. Mr. Gansler said he was helping Navient “get its narrative out there.”

And in March, Navient joined the Republican and Democratic Attorneys General Associations, paying $15,000 to each to do so. It was the company’s first such contribution to the groups.

Three months later, Mr. Remondi spoke at the Democratic association’s summer policy conference in Seattle, joining a panel discussion about how to help borrowers avoid a lifetime of debt.

For about 15 minutes — until Ellen Rosenblum, the Oregon attorney general, who moderated the panel discussion, cut him off — Mr. Remondi spoke about Navient’s efforts to help federal loan borrowers navigate their repayment options and avoid falling behind, according to meeting attendees.

His pitch failed to sway Xavier Becerra, California’s attorney general, who had one of his top aides on the panel with Mr. Remondi. Three weeks later, his office sued Navient.

Right after the lawsuit was announced, Senya Merchant, a program manager at the Center for American Progress, a progressive advocacy group, sent a message to one of Mr. Becerra’s advisers.

“Do you think this would supplant the C.F.P.B. suit in case that one gets dropped?” Ms. Merchant wrote in an email, which was obtained through a public records request.

“I can’t speculate,” replied the adviser, Sarah Lovenheim, “but that’s a good question.”