Gov. Dannel Malloy’s tumultuous year has only become more turbulent, as federal investigators have probed into alleged improprieties in his 2014 re-election campaign’s fundraising.

At issue are the mixing of money from the Connecticut Democratic Party’s separate funds for state and federal races and the tenets attached to accepting funds from the Citizens’ Election Program, Connecticut’s clean-election fund. Malloy used $6.5 million from the CEP in his successful 2014 re-election campaign, but attached to those millions was an affidavit, signed by Malloy, pledging that his campaign would use no funds additional to the CEP grant.

The alleged illegality began with three pro-Malloy mailings, paid for by roughly $250,000 from the Connecticut Democratic Party’s fund. The State Elections Enforcement Commission settled its own investigation into the party’s alleged wrongdoing for a payment of $325,000, but a federal grand jury began a separate investigation in July and has begun to issue subpoenas.

Malloy has, for the most part, refrained from commenting on the investigation, noting that any comments he makes could influence the outcome of the probe.

“I certainly understand that people have the right to look at whatever they want to look at, and understand what transpired,” Malloy said at a press conference earlier this month. “I think people have a right to take a look, they’re taking a look, we’ll see where that goes, and where it ends.”

Emails obtained by the Connecticut Post in August show that the federal probe into Malloy’s re-election campaign has been brewing even before he eked out a narrow victory over Tom Foley, the Greenwich businessman whom the Republicans nominated. Days before voters went to the polls, the Post’s emails show, federal attorneys sought evidence that the Malloy campaign had agreed not to use outside funding, and communication about the campaign’s use of funds continued apace throughout 2015.

The state’s Republican leadership, already giddy at Malloy’s deep unpopularity in Connecticut, have pounced on the federal probe to attack the governor. Senate Minority Leader Len Fasano ’81, the state’s top-ranking Republican, challenged Malloy to release the emails subpoenaed by the State Elections Enforcement Commission as part of their investigation into the campaign.

“Gov. Malloy is still withholding his own emails and state Democratic Party emails that have not just been requested, but subpoenaed by his own state’s elections enforcement officials,” Fasano said in a statement. “In what kind of warped reality can a governor challenge someone to release emails when his own withholding of emails is currently being investigated by the feds?”

The controversy surrounding his re-election campaign comes at a bad time for Malloy, the former mayor of Stamford, who moved into the governor’s mansion in January 2011. Years of fiscal travails in Hartford — a seemingly interminable budget crisis, complete with mass layoffs and tax hikes — have made Malloy the least popular Democratic governor in the country, according to a Morning Consult poll released in May. Sam Brownback, the Republican governor of Kansas, beats Malloy out to the title of the overall least popular governor.

Yet Malloy’s domestic unpopularity is at apparent odds with his national prominence. Not only does he serve as the chairman of the Democratic Governors’ Association, making him one of the most prominent figures in the Democratic establishment; he has also become one of Hillary Clinton’s LAW ’73 top surrogates, and is widely tipped to receive a cabinet appointment — cutting short his second term by two years — should she win the presidency in November.

Connecticut’s lieutenant governor, who would take charge should Malloy move to Washington, is Nancy Wyman, a former state comptroller who joined Malloy on the Democratic ticket in 2010.