New York Attorney General Barbara Underwood sued President Donald Trump, three of his adult children and their charitable foundation Thursday, claiming "a pattern of persistent illegal conduct" for more than a decade.

Underwood said the Donald J. Trump Foundation engaged in "extensive unlawful political coordination with the Trump presidential campaign."

She also alleged "repeated and willful self-dealing transactions to benefit Mr. Trump's personal and business interests." She said the foundation violated "basic legal obligations for non-profit foundations."

In addition to Trump and the foundation, Underwood is suing Donald Trump Jr., Eric Trump, and their sister Ivanka Trump, a senior adviser to the president.

The family members are all board members of the foundation, according to Underwood, who filed suit in state court in New York City. Underwood said the board of directors "existed in name only," since it never met after 1999 and did not approve of any grants.

Instead, Trump himself "made all the decisions related to the Foundation," according to the AG's office.

"As our investigation reveals, the Trump Foundation was little more than a checkbook for payments from Mr. Trump or his businesses to nonprofits, regardless of their purpose or legality," Underwood said in a statement.

"This is not how private foundations should function and my office intends to hold the Foundation and its directors accountable for its misuse of charitable assets."

The attorney general, a Democrat, said that the president used the foundation's name and funds it raised from the public to pay off his legal debts, promote Trump-branded hotels and other businesses "and to purchase personal items."

Those allegedly questionable payments included a $100,000 payment to settle legal claims against the president's Mar-a-Lago resort in Florida, a $158,000 payment to settle claims related to a hole-in-one tournament at the Trump National Golf Club in Westchester County and $10,000 at a charity auction to buy a painting of Trump that was later displayed at his Trump National Doral in Miami.

And, at Trump's behest, the foundation "illegally provided extensive support to his 2016 presidential campaign by using the Trump Foundation's name and funds it raised from the public to promote his campaign," Underwood's office said.

The AG said the foundation raised more than $2.8 million at a nationally televised event that Trump hosted after he declined to participate in a presidential debate in Iowa.

Trump's campaign director at the time, Corey Lewandowski, "in violation of state and federal law," then "dictated the timing, amounts, and recipients of grants by the Foundation to non-profits," the AG's office said.

The suit said at least five grants of $100,000 apiece were awarded by the foundation to groups in Iowa just days before the Feb. 1, 2016, presidential caucuses there.