Hemmed in by solid Republican opposition, the Senate seems ready to hand a fresh defeat to President Barack Obama by blocking an election-year bill increasing the federal minimum wage.

Democrats, aware that the measure faces all but certain rejection Wednesday in the chamber they control, plan to use the vote to buttress their campaign theme that the GOP is unwilling to protect financially struggling families.

“Americans understand fairness, and they know it’s unfair for minimum-wage workers to put in a full day’s work, a full month’s work, a full year’s work, and still live in poverty,” the measure’s sponsor, Sen. Tom Harkin, D-Iowa, said Tuesday.

Harkin’s bill, an Obama priority, would gradually raise the $7.25 hourly minimum to $10.10 over 30 months and then provide automatic annual increases to account for inflation. Democrats argue that if fully phased in by 2016, it would push a family of three above the federal poverty line — a level such earners have not surpassed since 1979.

They also say the minimum wage’s buying power has fallen. It reached its peak value in 1968, when it was $1.60 hourly but was worth $10.86 in today’s dollars.

Republicans say the Democratic proposal would be too expensive for employers and cost jobs. As ammunition, they cite a February study by the nonpartisan Congressional Budget Office that estimated the increase to $10.10 could cost about 500,000 jobs — but also envisioned higher income for 16.5 million low-earning people.

Citing those job loss figures, Senate Minority Leader Mitch McConnell, R-Ky., said Tuesday, “When it comes to so many of their proposals, Washington Democrats appear to prioritize the desires of the far left over the needs of the middle class.”

Democrats needed 60 votes Wednesday to begin Senate debate. To prevail, they would need support from at least six Republicans, which seemed beyond reach.

“I can’t give you a number, but I’m confident” Democrats won’t succeed, Sen. John Cornyn, R-Texas, his party’s vote-counter, said after GOP senators met Tuesday.

Sen. Susan Collins of Maine, one of the few Republicans considered potentially willing to let debate begin, said Tuesday she expected to oppose the legislation, saying it would hurt companies. Sen. Bob Corker of Tennessee was the only Republican to publicly state he probably would vote to allow the bill to be considered.

Sen. Mark Pryor, D-Ark., who faces a tough re-election and has said the $10.10 increase is excessive, will miss Wednesday’s vote. He will be in Arkansas due to deadly storms there, an aide said.

The legislation is opposed by business groups including the National Council of Chain Restaurants and the International Franchise Association. The National Restaurant Association has hundreds of members at the Capitol this week lobbying lawmakers on several issues, including opposition to a higher minimum wage.

Also opposed were conservative organizations including Heritage Action and Americans for Prosperity, which is backed by Charles and David Koch. The billionaire brothers are spending millions this year to unseat congressional Democrats, and Senate Majority Leader Harry Reid, D-Nev., and his allies are casting them as unfettered villains.

Wednesday’s vote seemed sure to add minimum wage to a scrap heap of Democratic bills that had a shared theme of economic fairness.

Others that have splattered against GOP roadblocks would restore expired benefits for the long-term unemployed and pressure employers to pay men and women equally. Democrats plan future votes on bills easing the costs of college and child care.

Even if the minimum wage bill survived the Senate, opposition from Republicans running the House made it unlikely that chamber would debate it this year.

Underscoring the political value they envisioned from the minimum wage fight, Harkin and other Democrats said if the measure was defeated Wednesday, the Senate would vote on it again this year.

According to the federal Bureau of Labor Statistics, about two-thirds of the 3.3 million people who earned $7.25 an hour or less last year worked in service jobs, mostly food preparation and serving.

More than 6 in 10 of those making $7.25 or under were women, and about half were under age 25. Democrats hope their support for a minimum wage boost will draw voters from both groups — who usually lean Democratic — to the polls in November, when Senate control will be at stake. The GOP’s hold on the House is not in doubt.

Harkin’s bill would also gradually increase the minimum wage for tipped workers like waiters to 70 percent of the minimum for most other workers. It is currently $2.13 hourly, which can be paid as long as their hourly earnings with tips total at least $7.25.

The minimum wage was first enacted in 1938 and set at 25 cents.

Congress has passed nine laws slowly increasing it, including one each decade since the 1980s. The minimum has been $7.25 since 2009.

(AP)