After months of delay, Senate Majority Leader Harry Reid will hold a critical test vote on legislation that would raise the minimum wage by nearly 40 percent, to $10.10 an hour.

The bill anchors a Senate Democratic agenda that focuses on income inequality. Democrats say the current minimum hourly wage of $7.25 deprives workers of a decent standard of living.

Like other legislation on the Democratic agenda, however, the minimum wage bill has no chance of passing the Republican-led House.

In fact, the bill won’t even make it on to the Senate floor for debate because Republicans oppose it and are all but guaranteed to deprive Democrats of the 60 votes needed to prevent a filibuster.

Republicans believe a minimum wage hike will raise the unemployment rate, and they cite a report from the non-partisan Congressional Budget Office that found half a million jobs would be lost under the Democratic plan to phase in an increase to $10.10 per hour.

But the legislation isn’t meant to pass, Democrats have said. Instead, they said, they’ll use it to contrast their governing philosophy with the GOP ahead of the critical November elections. Democrats hope to portray Republicans as unconcerned with the struggles of the middle and lower classes.

Reid, a Democrat from Nevada, said Monday that Republicans are under the control of the ultra-rich Koch brothers, who support a political action committee that has spent more than $30 billion hurting Democratic candidates with negative political advertising.

Earlier this month, Senate Republicans blocked a Democratic bill that aimed to ensure men and women are paid equally by increasing federal oversight of hiring by private companies and making it easier to sue employers over pay differences.

“As the Senate turns its attention to an increase of the federal minimum wage, is there any question as to whether the Republicans will once again do the Koch brothers’ bidding and not give millions of American a fair shot at livable wages?” Reid said Monday.

But even some Senate Democrats are not fully supportive of the minimum wage measure.

Sen. Mark Pryor, D-Ark., said the $10.10 minimum is too high. Sens. Mark Warner of Virginia, Mary Landrieu of Louisiana and Tom Carper of Delaware have also indicated a lower hike should be considered.

Earlier this month, Sen. Susan Collins, R-Maine, said she was working with a group of Democrats on a compromise plan involving a lower wage hike coupled with incentives for small businesses.

Reid, however, said he would not consider anything less than an increase to $10.10.

Reid has continually postponed a vote on the bill, in part because of pushback from the small group of Democrats who aren’t fully on board. Most of them face tough re-election bids, and a minimum wage vote could be politically treacherous. But in recent polls a few of the lawmakers have rebounded, which likely prompted Reid to act now.