An informal adviser to former Gov. Andrew M. Cuomo has formed a new outside group that appears designed to boost his campaign for mayor of New York City, according to state records.

Unlike a pro-Cuomo super PAC that has already spent millions of dollars directly supporting the candidate, the second group, Restore Sanity NYC, is registered as a nonprofit technically engaged in issue advocacy.

That legal status means Restore Sanity NYC cannot directly campaign for a candidate without running afoul of the law. But the structure has advantages, allowing the group to raise and spend unlimited sums without disclosing its donors.

A campaign flier from the nonprofit that arrived in mailboxes this week, for instance, implored voters to “join the majority of New Yorkers who agree on how to get our city back on the right direction.”

While it did not name Mr. Cuomo, it echoed the former governor’s criticism of calls to “defund the police,” stressed the need to “get big things done” — a frequent Cuomo tagline — and singled out the new LaGuardia Airport, a redevelopment project he has made a centerpiece of his campaign.

There may be good reason for the group’s lack of transparency.

State records show that the group was registered in April by Chris Coffey, an informal Cuomo adviser whose business partner is the campaign’s current political director.