District residents could soon vote to free the city from some congressional spending restrictions if the D.C. Council passes legislation to be introduced Tuesday by Chairman Phil Mendelson.

The proposal represents a sharp turn in the District’s march toward budget autonomy, a key goal of voting rights activists and city officials that has been embraced by some congressional Republicans but complicated by threats of amendments targeting District affairs.

Mendelson’s bill would authorize a vote in the next citywide election on changing the District charter to remove Congress’s power over most local spending. If voters approve the measure and it passes a 35-day congressional review period, the city would be free to spend its locally raised tax dollars largely without Capitol Hill’s involvement.

The new strategy, masterminded by activist groups D.C. Vote and the D.C. Appleseed Center for Law and Justice, is controversial. Officials from those groups confirmed the plans Monday; Mendelson (D), through a spokeswoman, declined to comment on the legislation before briefing his colleagues Tuesday morning.

There are concerns it could short-circuit efforts by Del. Eleanor Holmes Norton (D-D.C.) and Mayor Vincent C. Gray (D) to have Congress pass a bill granting budget autonomy — efforts supported by House Majority Leader Eric Cantor (R-Va.) and Rep. Darrell Issa (R-Calif.), chairman of the House Oversight and Government Reform Committee. There are also concerns, including from the city’s own attorneys, that the maneuver is legally dubious and could be subject to a court challenge.

But Mendelson and activists think a “two-track approach” of pursuing a charter referendum while congressional talks proceed offers the best chance to give the city budget autonomy without having to risk a congressional compromise that could affect local priorities such as gun laws and abortion funding.

“I think all of us wanted to give that effort an opportunity to succeed,” said Ilir Zherka, D.C. Vote’s executive director. “But it’s going to be harder and harder to get a budget autonomy bill through Congress, and we believe that the District of Columbia needs to embrace a new strategy.”

The referendum maneuver was quietly floated behind the scenes earlier this year, after the National Right to Life Committee announced that it would “score” any budget autonomy vote. That threat made it unlikely a bill would emerge from the House without amendments that local officials have found unpalatable in the past, such as a ban on using local money to fund abortions for low-income women.

Both the congressional legislation and the referendum would allow the city to spend nearly $6 billion a year in local tax dollars without waiting for a congressional appropriation. Among other benefits, it would remove the ongoing threat that a federal government shutdown would also shut down city government.

But some doubt whether the District has the authority to make such a dramatic change to its charter absent an act of Congress. A 23-page legal memorandum prepared for Attorney General Irvin B. Nathan last October, responding to the initial D.C. Appleseed and D.C. Vote proposal, found that it would not be permissible to use the amendment-by-referendum procedure to grant the city budget autonomy.

Jonathan Turley, a George Washington University law professor who has written about District autonomy, also questioned the strategy.

“The congressional review period was designed for standard measures of self-governance,” Turley said. “It was not contemplated that the charter itself would be changed through this standard legislative means. I expect there would be many people in Congress that would take a dim view of that interpretation.”

Walter Smith, D.C. Appleseed’s director, said his group and attorneys it has consulted think the District has the power to free its local tax dollars from congressional oversight.

“I think a lot of people are unaware of just how broad the council’s authority is to amend the [charter],” Smith said. While the city could not, for instance, end congressional review of its laws or impose a commuter tax, he said, “the budget process is not one of the areas that’s off limits — it’s just as simple as that.”

Aside from the legal questions, the political considerations could be troublesome. Gray and Norton balked this year when presented with the strategy, according to two people familiar with the situation, leading to a delay in its rollout. Asked about the proposal Monday, Gray spokesman Pedro Ribeiro said only, “The mayor supports budget autonomy.” A spokesman for Norton did not respond to a request for comment.

A Republican congressional aide who requested anonymity to speak frankly about the situation said the strategy could send a counterproductive message to the Hill.

“If there’s this effort to basically do an end-run around Congress . . . it will certainly complicate the argument within Congress on whether the District can be trusted with this authority,” the aide said.

Smith rejected that notion: “This can’t be an end run, because at the end of the day, because of the Constitution, Congress always has the final say.”

Should the council pass the bill before the current term ends in December, voters could see the question on the ballot in the spring — during a special election to fill the at-large council seat Mendelson is expected to vacate after his likely November election as chairman.