Republican presidential nominee Donald Trump. REUTERS/Carlo Allegri

Questions over the Trump Foundation's illegal contribution to a political group tied to Florida's attorney general do not appear to be going away.

The Tampa Bay Times is urging the US government to investigate potential connections between Donald Trump's charity and Florida Attorney General Pam Bondi.

"Since Florida prosecutors will not touch this mess, the Justice Department is the only option," the newspaper's editorial board wrote on Thursday.

"The appearance of something more than a coincidence is too serious and the unresolved questions are too numerous to accept blanket denials by Bondi and Trump without more digging and an independent review," the board wrote.

The question at hand is whether the Trump Foundation made the $25,000 contribution to stave off a Florida state inquiry led by Bondi in 2013 that was related to allegations against Trump University — the New York billionaire's embattled entrepreneurship business.

The Tampa Bay Times called into question the timing of Bondi's decision not to pursue any further investigation into the matter, saying it "simply does not look right and deserves an independent look to reassure Floridians that the state's top legal officer did nothing wrong."

The Washington Post reported last week that the IRS slapped the Trump Foundation with a fine over that $25,000 gift. A Trump Organization senior vice president told The Post that the donation was "an honest mistake" and that the contribution wasn't properly listed.

Bondi has maintained that suggestions of collusion are politically motivated, and she declared she "will not be collateral damage in a presidential campaign" or "be a woman bullied by Hillary Clinton.''

During a Republican primary debate in August 2015, Trump boasted about calling in favors from his political allies in exchange for campaign contributions.

"When they call, I give. And you know what? When I need something from them, two years later, three years later, I call them, and they are there for me," Trump said.

Trump told reporters earlier this week that he "never" discussed the matter with Bondi when she called him in 2013 seeking a donation.