Is the minimum wage a winning “wedge” issue? The Service Employees International Union (SEIU) certainly thinks so.

Recently, the union announced plans for a massive voter engagement drive for the 2018 election cycle focusing specifically on the Midwest. However, its method of convincing voters to push Democrats into power isn’t revolutionary. The union is attempting to turn the minimum wage into a major election issue — yet again.

Politicos take note: The past two election cycles have shown that the minimum wage doesn’t win majorities. Voters may support minimum wage hikes when polled and not informed of the consequences, but this enthusiasm doesn’t translate into votes for supportive candidates.

In 2014 and 2016, control of the Senate was up for grabs, and there were also heavily-contested gubernatorial races in blue and purple states. Public Policy Polling (PPP), the left-leaning polling group based in Raleigh, N.C., released a memo a few weeks before election day in 2014 that claimed opposition to minimum wage hikes could be a “decisive issue” in six key states: Illinois, Wisconsin, North Carolina, Iowa, Kentucky, and Louisiana. Republican criticism of a minimum wage hike was supposed to reduce their support among voters by as much as 30 points.

The PPP poll was wrong: Each of the six candidates who were skeptical of or opposed to a higher minimum wage still won their race. The “minimum wage as wedge issue” scheme failed to take hold in state after state.

In 2016, the SEIU and its “Fight for $15” movement tried to push a minimum wage wedge once again.

My organization used Google’s consumer survey tool to poll people who planned to vote in each of the seven battlegrounds states targeted by PPP and the National Employment Law Project Action Fund, a union-backed advocacy group. In North Carolina, more than 40 percent of respondentssaid they were no more or less likely to vote for a candidate based on their opposition to minimum wage. Those who were swayed one way or the other based on a candidate’s minimum wage stance were of roughly equal proportion — canceling each other out.

Across all seven battleground states, 70 percent of those who planned to vote indicated that a candidate’s minimum wage opposition would either have no impact on their vote, or increase their likelihood to vote for a candidate.

The post-Election Day results from 2016 provide further evidence of the failed wage-wedge strategy. Labor groups pledged to “knock on tens of thousands of doors” with the minimum wage message to no avail. Of the 20 U.S. Senate races where the Republican incumbent was on the record voting against a $10.10 federal minimum wage in 2014, only two (Mark Kirkand Kelly Ayotte) lost their seat. And those members were slated to lose for a host of other reasons. In Indiana, Rep. Todd Young — who voted against an increase when he was in the House — won his race for U.S. Senate.

But history doesn’t seem to matter much to SEIU bosses, who hope the third time is the charm. This time, the odds are even more stacked against the union.

Republicans control 34 governorships, the House, the Senate, and the White House. Unemployment is at 4.4 percent. By plotting a path further to the left on the minimum wage, Democrats are alienating themselves from voters already uninterested in what they’re selling. The evidence backs this up: Politico reports this week, based on evidence from polling and focus groups, that the $15 issues tests poorly outside the Democratic base.

Most economists oppose a $15 minimum wage, and the recent evidence shows why. Bombshell studies from economists at the University of Washington and Harvard Business School have shown the negative impacts of extreme minimum wage hikes contemplated by Democrats. In Seattle, the city’s rising minimum wage decreased earnings for affected workers by $125 per month; in San Francisco, the minimum wage increase closed numerous businesses. (Many stories are available at Facesof15.com.)

Democrats can’t even get all of the members of their own party to sign on to the “Raise the Wage Act.” This legislation, introduced by Sen. Bernie Sanders, would increase the federal minimum wage by 107 percent from $7.25 to $15 an hour. The bill has one sponsor and 30 co-sponsorsout of 48 members of the Democratic Caucus in the Senate. The bill does not have a single Republican Senator as a co-sponsor.

Some wedge issue.

Michael Saltsman is managing director at the Employment Policies Institute, which receives support from businesses, foundations and individuals.