WASHINGTON – With a showdown approaching today or Friday, Senate Democrats are publicly predicting that they’ll block a minimum-wage hike this year so long as Republicans insist that it be tied to slashing taxes on inheritances for a select group of wealthy Americans.

Behind the scenes, though, the Senate Democratic leadership was scrambling Wednesday to lock down commitments from a handful of wavering senators who’ve been put in difficult binds by the Republican-drafted legislation, which already has passed the House of Representatives.

The bill would raise the minimum wage from $5.15 to $7.25 per hour over three years. It also would sharply reduce the tax on inherited estates, as well as some other taxes. More than 6 million Americans would gain directly from the higher wage. About 8,200 heirs would gain $1.4 million each from the estate-tax cut, according to the Center on Budget and Policy Priorities, a liberal research center staffed by former government budget analysts.

The bill contains various “sweeteners” to make it hard for key Democrats to vote against, including tax breaks for the timber industry in Washington state and miners in West Virginia, and bond-related perks for Arkansas. Senators from those states facing potentially tough re-election fights in November – including Maria Cantwell, D-Wash., and Robert Byrd, D-W.Va. – may be loath to block the legislation for fear that losing those special breaks could cost them votes back home.

“It’s kind of a political box they’ve tried to put us in,” said Sen. Mark Pryor, D-Ark., adding that he’d been in private meetings with colleagues on both sides of the aisle all day. “It’s such a big, enormous, wide-ranging proposal, there are a lot of merits to consider here.”

Senate Republicans could fend off a Democratic filibuster and pass the wage and tax package this week before leaving town for a month-long recess if all 55 of their members support it – and they pick up five Democrats. Two Republicans have indicated that they’ll consider breaking ranks, but seven Democrats are considered possible defectors.

Republican Majority Leader Bill Frist, R-Tenn., has given Democrats an ultimatum: Agree to the package deal this week or get no minimum-wage hike this year.

“This is the one shot,” Frist said. “There will be no second chances. No last-minute side deals.”

Democrats say Frist might change his tune after the August recess if the minimum-wage issue looks as if it could be an election spoiler, however.

For Democrats – and a few dozen moderate Republicans in Rust Belt states or otherwise competitive races – raising the minimum wage is a potent campaign issue. It hasn’t been increased since 1997. Since then, inflation has cut its purchasing power by 26 percent.

In the same time span, Congress has raised lawmakers’ salaries by about $32,000, three times the annual salary of someone who earns the minimum wage.