Future D.C. government workers who live outside the city would be forced to pay part of their income back to the District under a plan lawmakers will consider Wednesday, though high-powered opposition has already emerged and is girding for a fight.

The measure, which has not yet faced a D.C. Council vote, would require new employees to agree to pay the city 4 percent of their government salaries if they live or move outside D.C.

The requirement wouldn't apply to current city employees.

"This is another method to try to tax income at its source," said Ward 2 Councilman Jack Evans, one of the measure's sponsors. "We have to be creative, so one way of being creative is to tax people who work for the District government who live in other jurisdictions."

Along with Evans, four other legislators have publicly endorsed the plan.

But the proposal drew heavy criticism from organized labor, a key political constituency in the District.

"I thought it was one of the most ridiculous, asinine proposals I've heard in many a year," said Geo Johnson, executive director of the D.C. chapter of the American Federation of State, County and Municipal Employees. "We're prepared to go at this with everything we have."

Kristopher Baumann, the leader of the police union, also dismissed the measure.

"We are already down over 300 police officers," said Baumann, who added that more officers are poised to retire. "This legislation would severely damage our ability to fill those positions. Only someone completely disconnected from the issues or someone posturing for future political office -- at the expense of public safety -- would propose something this foolish."

Pedro Ribeiro, a spokesman for Mayor Vincent Gray, said the administration was reviewing the proposal, though he noted Gray has historically "preferred incentive-based approaches rather than punitive ones."

The bill has languished in committee since March 2011, and its resurfacing has come amid renewed calls for the city to have the authority to impose a commuter tax.

Earlier this year, Evans introduced legislation that was designed to push Congress to re-evaluate its stance on a commuter tax, which the Home Rule Act has prohibited the city from enacting.

In turn, the District has long complained that nonresidents sap its infrastructure during the workday and pay nothing out of their incomes to maintain the city.

District officials have said a commuter tax would prove lucrative. Natwar Gandhi, the city's chief financial officer, said D.C. would have made about $800 million last year if it had been able to levy a commuter tax.

Top Republicans on Capitol Hill have indicated a willingness to consider changes, though any shifts would almost certainly face intense opposition from the Maryland and Virginia congressional delegations.