WASHINGTON — House Republicans haven’t even officially unveiled their massive plan to overhaul the tax code but the top Republican in the Senate is already pronouncing it dead.

Senate Minority Leader Mitch McConnell, R-Ky., said Tuesday he sees no hope for enacting tax overhaul legislation this year. He blamed Democrats for trying to use the issue to raise revenue by $1 trillion.

McConnell said the object of overhauling the tax code should be making the nation more competitive, not raising more money for the government.

McConnell’s remarks came a day before the Republican chairman of the tax-writing House Ways and Means Committee, Rep. Dave Camp of Michigan, was to unveil a massive tax plan three years in the making.

Camp’s plan would cut income tax rates but impose a new surtax on some high-income families, said a GOP aide who wasn’t authorized to discuss the plan by name and spoke on condition of anonymity. The top income tax rate for most families would be lowered from 39.6 percent to 25 percent. However, the plan would impose a new 10 percent surtax on some earned income above about $450,000.

The new surtax would not apply to capital gains or dividends, sparing many of the super-rich who make the bulk of their money from investments.

The plan had little chance of becoming law in this year even before McConnell’s remarks. But it could become a political document for House Republicans to show what they stand for, and for Democrats to attack, as the midterm elections approach in November.

House Republicans have touted the upcoming plan as a major overhaul of the tax code that would dramatically lower tax rates for individuals and corporations, but recoup the revenue by eliminating or reducing popular tax breaks.

Overall, the plan is designed to raise about the same amount of tax revenue as the current system, though the system would be much simpler.

“Today’s tax code is too costly, too complex and too time-consuming,” Camp’s office said in a statement Tuesday. “America needs a tax code that will spur economic growth, create jobs and put money back in the pockets of hardworking taxpayers.”

It is an important political point for Republicans that the plan is not seen as a big giveaway to the rich. The new surtax on high-paid workers would partially offset the massive rate cut. But the plan would have to raise other taxes on the rich to avoid shifting more of the tax burden to middle- and low-income families.

The issue of whether to increase overall tax revenue is a major sticking point among Republicans and Democrats. Most Republicans in Congress adamantly oppose anything that looks like a tax increase, while Democratic leaders insist that any attempt to overhaul the tax code raise additional revenue.

President Obama and Senate Majority Leader Harry Reid, D-Nev., have said they want to target tax breaks enjoyed by some corporations and the wealthy.