Former D.C. mayor Vincent C. Gray speaks in Washington. Associates say he is considering reentering politics. (Alex Brandon/AP)

A year after voters rejected his reelection bid, former mayor Vincent C. Gray is considering mounting a campaign for the D.C. Council, according to four people familiar with his thinking.

Gray, whose 2010 mayoral campaign has been the subject of a long-standing federal investigation, is eyeing two potential races next year: the at-large seat occupied by Vincent B. Orange (D) and the Ward 7 seat held by Yvette M. Alexander (D), according to the associates, who spoke on the condition of anonymity to speak freely about the matter.

Gray, 72, who resides in Ward 7, declined to comment when asked about returning to the city’s political arena 18 months after Mayor Muriel E. Bowser (D) defeated him in the Democratic primary.

However, an associate who has talked with the former mayor about the races said Gray has been buoyed by expressions of encouragement from people he meets in his daily travels. The associate described Gray (D) as having grown more serious about the possibility of running, and this person is also confident that the former mayor could raise enough money to mount a formidable campaign.

Prior to his election as mayor, Gray served as Ward 7’s representative on the council and then was elected chairman.

“This is the real deal,” the associate said. “The moment he announces, he will not have a single worry when it comes to fundraising.”

At the same time, a person familiar with Gray’s thinking said that the former mayor’s conversations about a possible campaign are informal at this stage and that he remains undecided about returning to public life. Gray, the person said, misses government work and has been flattered by supporters’ encouragement.

Nominating petitions are set to be available in January, and the city’s Democratic primary is scheduled for June 14.

As a candidate, Gray probably would face questions about the unresolved federal investigation into the 2010 campaign, in which he defeated then-Mayor Adrian M. Fenty.

Soon after Gray took office, investigators began looking into whether he had orchestrated a scheme to illegally funnel more than $660,000 into his reelection bid. While Gray has never been charged and has denied wrongdoing, a half-dozen of his associates have pleaded guilty to an array of charges.

When he ran for reelection, Gray for several months led a field of Democratic candidates, including Bowser, vying to unseat him. But Bowser defeated him by more than 10,000 votes after then-U.S. Attorney Ronald C. Machen Jr. announced a few weeks before the Democratic primary that a business executive had implicated Gray in the creation of an illegal “shadow” campaign.

Machen resigned as U.S. attorney in April, though the probe into Gray’s 2010 campaign remains unresolved. Gray departed from office thinking he would have won reelection had it not been for the investigation, a sentiment shared by many of his most ardent supporters, some of whom hope he returns to politics.

“He needs to come back into the politics in the city,” said Barbara Morgan, a longtime activist in Ward 7. “Vince is a good person. The city persecuted Vince Gray, and the city owes him another chance.”

But the ongoing investigation is likely to remain an issue for voters who hesitated to support Gray during the mayoral race.

Barbara Savage, another Ward 7 activist, is a former Gray supporter who did not back his reelection campaign, in part because of the investigation. At this point, Savage said she does not know whether she could support him if he ran for the council.

“I don’t want to jump out there, and then I’m disappointed because the U.S. attorney drops a bombshell,” she said. Referring to the prosecutors, she also said: “I don’t think they have anything. I don’t think it’s fair to him. I don’t think it’s fair to people like myself.”

A person familiar with the Gray’s thinking said that his decision about a campaign is not dependent on prosecutors resolving their investigation. Gray ran for reelection as mayor under the same cloud.

If he runs for the Ward 7 seat, a district that encompasses neighborhoods including Deanwood and Hillcrest east of the Anacostia River, Gray probably would face Alexander, an incumbent whom he endorsed when she ran. Asked about a potential Gray challenge, Alexander said the field of candidates remains in flux and she is unsure who is running.

Gray won nearly 60 percent of the Ward 7 vote in the 2014 Democratic primary. In 2010, against Fenty, Gray won 82 percent of the vote in Ward 7.

As an at-large candidate, Gray would run citywide.

A onetime member of Gray’s cabinet, who has been in his presence at public events, said the former mayor has appeared to grow more interested in seeking office as the months have passed and as people have encouraged him to run. “At first he was ­non-responsive,” the former aide said. “And then he started saying he would consider it. It wasn’t like he was being polite. If he wasn’t going to do it, he’d tell you. He’s pretty direct that way.”