AUGUSTA — A broad coalition of business groups on Tuesday promised a robust campaign for their proposal to raise the minimum wage to $10 an hour by 2020, a proposal that competes directly with a citizen-initiated ballot question that would raise the wage to $12 an hour by the same year.

The proposal, which union-backed interest groups described as a “cynical political ploy” to defeat a citizen initiative already approved for the November ballot, must first become a bill for lawmakers to consider it this session. If the Legislature approves it, the proposal will be placed on the ballot alongside the higher wage proposal supported by unions and the Maine People’s Alliance, a progressive activist group.

Recent polling suggest that there’s wide appeal for the $12 an hour initiative.

Groups supporting the higher wage increase have described the business-backed proposal as a smokescreen to confuse voters. But Peter Gore, vice president of the Maine State Chamber of Commerce, said businesses won’t sit on the sidelines if they’re successful getting the proposal on the ballot.

“We will help pass it if it gets on the ballot,” Gore said. “If that wasn’t clear, let me make it clear. We will promote it and work to pass it.”

First business groups will have to convince lawmakers to put it on the ballot. While Republicans, who control the Senate, will likely support the business groups’ proposal, Democrats control the House of Representatives. Two Democratic leaders, Sen. Justin Alfond, of Portland, and Rep. Jeff McCabe, the House majority leader, have already indicated that the citizen initiative should stand alone in November.

Still, members of the 15-member coalition said Wednesday that the collective voice of 10,000 small businesses can be persuasive.

“We’re coming to the table saying this is a viable solution that we think will work,” said Curtis Picard, director of the Retail Association of Maine. “We know that legislators are already getting dozens and dozens of calls from our members across the state … We think they’re going to listen to the people of Maine. … This is going to increase the minimum wage in a sustainable way.”

Backers of the $12 citizen initiative countered that business groups worked hard to defeat previous minimum wage bills in the Legislature.

“They opposed every minimum wage bill on the docket last year,” said Matt Schlobohm, executive director of the Maine AFL-CIO, a federation of organized labor organizations. “This is a cynical political ploy designed to undermine and derail a strong minimum wage initiative.”

Schlobohm also referenced an email sent by the Maine Restaurant Association CEO Greg Dugal urging its members to contact legislators. In the email, Dugal acknowledges that the higher wage proposal will likely be approved by voters.

“We have concluded as an association that trying to defeat this referendum with the resources we have available, both monetarily and with limited staff, would be pretty close to impossible,” wrote Dugal in the Feb. 18 email. “It has been eight years since the last minimum wage increase and our detractors will use that against us and most likely will be successful.”

Dugal also noted a provision in the citizen initiative that will eventually eliminate a tipped credit that allows restaurant owners to pay lower hourly wages to food servers, bartenders or other tipped employees. Dugal described the phaseout of the tipped credit as a mortal threat to Maine restaurants.

The business group’s proposal would raise the minimum wage from $7.50 to $8.50 in 2017 with 50-cent annual increases to $10 an hour by 2020. The citizen initiative already on the ballot would raise the state’s minimum wage from $7.50 to $9 an hour in 2017, followed by annual increases to $12 an hour by 2020.

Polls consistently show that Maine residents support increasing the state’s minimum wage, which is 25 cents higher than the federal minimum and has not changed since October 2009.

The Maine People’s Alliance, the Maine AFL-CIO and the Maine Small Business Coalition gathered more than 75,000 signatures to place their $12-an-hour wage proposal on the ballot. The organizations ramped up the citizens’ initiative drive after the Legislature failed to approve any of several minimum wage bills last year that proposed a range of increases, to $8 an hour and up to $12.