Hunter Biden has racked up more than $10 million in legal bills over the past five years and could spend millions more as he confronts federal charges and the possibility of a costly trial.

The legal bills -- which have not been previously reported -- are a combination of fees incurred during a yearslong federal investigation of him, his divorce and his custody dispute in Arkansas, along with an aggressive new approach of filing lawsuits against his political detractors, according to people familiar with the figure.

Hunter Biden's allies had hoped that fundraising help would have come by now from top supporters of his father, President Joe Biden, but that hasn't happened.

And although people close to Hunter's legal team were discussing the idea of establishing a legal defense fund earlier this year, that hasn't materialized either, according to sources familiar with the effort.

"Nobody will help him financially," one person close to Hunter told CNN.

The financial burden is raising worry among friends about who'll foot the bill if he goes to trial on the gun charges, to which he pleaded not guilty on Tuesday.

But any debt would be a complicating political factor for his father's White House, already dealing with federal and congressional investigations into Hunter Biden's businesses. Hunter Biden's past attempts to raise money by selling high-priced pieces of artwork have stirred conflict-of-interest concerns, and the solicitation of more outside donations could be another target for scrutiny. The White House declined to comment for this story.

For Hunter Biden, the financial straits are tightening just weeks after he was hit with federal indictments on gun charges, and as he faces possible additional charges for alleged tax crimes. He had been expected to plead guilty in July to two misdemeanor charges in order to avoid a felony gun charge, but that deal collapsed under the scrutiny of a federal judge.

Special counsel David Weiss recently indicted him in connection with the purchase of a gun while he was addicted to drugs. The charges include making false statements on a federal firearms form and possession of a firearm as a prohibited person, for which he could face fines and time in prison.

Some members of Hunter Biden's team still hope the gun case can be resolved with a settlement, but there are currently no meaningful settlement discussions between his team and the special counsel, according to a source on Hunter's legal team.

"His legal bills are only going to grow as this gets closer to trial," said a second person familiar with the matter.

So far, a close friend of Hunter Biden, Hollywood attorney Kevin Morris, has covered many of his legal bills, a source close to Hunter Biden says. Morris has also spearheaded the more aggressive approach the Hunter team is taking against Republican adversaries -- a strategy they continue to employ despite mounting legal costs.

Over the past year, Hunter Biden has hired high-profile lawyer Abbe Lowell, who has helped him sue several of his detractors -- including Rudy Giuliani and attorney Robert Costello for allegedly hacking into his personal data, resulting in what he claims is the "total annihilation" of his digital privacy.

The more forward-leaning strategy represented a break with the White House, which had preferred that the president's son stay quiet amid ongoing investigations.

With House Republicans now opening a formal impeachment inquiry into his father, though, the White House is ramping up its own efforts to rebuke the idea Joe Biden was involved in his son's business dealings over the years.

That recalibration in approach has closed the chasm between the two camps, who now appear more aligned in their strategy, according to a person with direct knowledge of the situation. That person described the current approach by the White House as "all hands on deck."

The search for cash

In recent months, some supporters of Hunter Biden discussed setting up a legal defense fund, originally envisioned as a blind trust run by an ethics attorney who could closely monitor funds going in and out, according to people familiar with the matter.

Presented with that possibility, the White House bristled at the suggestion of a legal defense fund, leery of the idea they might be seen as breaching campaign finance laws, according to the sources. Those talks have gone quiet in recent weeks, those sources said.

With his lobbying and advisory business under the microscope, some of Hunter's income now comes from selling paintings for six-figure totals through a relationship with the Georges Bergès Gallery in New York City. (Sources told CNN two years ago the White House was involved in forming an agreement between him and Bergès to address any ethics concerns. The purchasers of his artwork were to be kept anonymous, with neither Hunter Biden nor the public knowing who purchased the work.)

But even there, debt figures in. In June, Hunter Biden reached a settlement to provide some of those paintings as financial compensation to Navy Lunden Roberts, the four-year-old daughter he fathered with an Arkansas woman, as part of a revised child support agreement. He had been paying $20,000 a month in child support -- totaling roughly $750,000 -- under a 2020 deal his attorneys argued he could no longer afford.

Hunter and his dad

Despite the public pains taken by the White House to distance the president from his son's lawsuits, father and son remain close -- speaking regularly by phone, traveling together, and appearing at official White House events together.

The politics are complicated. In a CNN survey conducted in late August by SSRS, 61% of US adults say they think Biden had at least some involvement in Hunter Biden's business dealings during his vice presidency, with 42% saying Joe Biden acted illegally, and 18% saying that his actions were unethical but not illegal. A 55% majority of the public says the president has acted inappropriately regarding the investigation into Hunter Biden over potential crimes, while 44% say that he has acted appropriately.

But with a year to go before the election, Biden's orbit worries most about the emotional impact the ordeal is having on the president.

"They're more worried about the toll it takes on the president," said one outside adviser. "You have to feel sorry for the guy -- he's been kicked in the teeth with family matters over and over."