Nearly two months before D.C.’s special election, local activists and officials on Thursday launched a campaign to mobilize voter turnout for a referendum that would give the District budget autonomy.

Home Rule Charter Amendment 8, as it’s known, was placed on the April 23 ballot through authorizing legislation passed through the D.C. Council at the end of last year. If passed, it would unlink the local budget from the congressional appropriations process, allow District officials to set their own fiscal calendar and spare the city anxiety over a government shutdown each time Congress nears a spending stalemate.

At the Thursday morning news conference, representatives from DC Vote and DC Appleseed, along with Council Chairman Phil Mendelson, laid out their course of action.

Over the next eight weeks, volunteers will spread the word about the charter amendment by canvassing homes, planting yard signs and speaking at community meetings. Proponents have also registered a special political campaign committee, the DC Budget Freedom Committee, with the director of campaign finance of the D.C. Board of Elections.

The referendum is expected to pass easily among residents who overwhelmingly support expanded rights and opportunities for self-determination for their city. Moreover, there’s no threshold that must be met for the referendum to be approved. But advocates said Thursday there still were advantages to having a large show of support among the roughly 300,000 registered voters.

“We’re sending a message,” Mendelson said.

Though it went unacknowledged on Thursday, local activists in favor of achieving budget autonomy by amending the city charter will likely use sizable voter turnout as leverage should the measure, once passed, be challenged, on Capitol Hill or in the courts.

In Congress, both chambers would have 35 days once the referendum is approved to pass a resolution disapproving of the outcome — and have that resolution signed by President Barack Obama. The window for congressional disapproval for charter amendments and legislation passed through the D.C. Council is always narrow, making it difficult for lawmakers to take advantage of their authority to overturn locally passed laws. There have been few instances of congressional disapproval.

More likely, any challenge would materialize in court. Referendum supporters, which include the entire D.C. Council, argue that the grass-roots effort is within legal bounds, as the Home Rule Charter has no explicit ban on residents giving themselves budget control.

They also say it’s the only way to ensure that budget autonomy for D.C. is achieved free of policy riders such as restrictions on abortion funding, which have thwarted efforts to pass a “clean” budget autonomy bill on Capitol Hill for the past year and a half.

Meanwhile, others are concerned about the legality, including D.C. Del. Eleanor Holmes Norton, Mayor Vincent Gray, D.C. Attorney General Irvin B. Nathan and GOP Rep. Darrell Issa of California, the chairman of the D.C.-focused Oversight and Government Reform Committee who has been the budget autonomy champion on Capitol Hill.

If the charter amendment passes, they say, it could come under fire for illegally attempting to circumvent Congress’ inherent control over the D.C. budget, as well as violating the act that forbids D.C. from spending funds before they are appropriated, in this case by Congress.

A better approach, they argue, would be to continue pushing a budget autonomy measure in Congress, where it would certainly not run afoul of any laws.