WASHINGTON – Republicans rammed an election-year, $46 billion tax cut for most of America’s employers through the House on Thursday, ignoring a White House veto threat in a debate both parties used to show voters how they would bolster the economy.

The near party-line 235-173 vote moved the bill to the Senate, where Democrats controlling the chamber are sure to ignore it. But the measure’s inevitable demise was secondary to the chance it gave each side to offer its prescriptions for creating jobs, echoing the battle that seems certain to dominate this fall’s battle for the White House between President Obama and Republican Mitt Romney.

“This is straight-up something to help small businesses keep more of their money while they’re having so much difficulty keeping the lights on, and instead giving them the ability to grow,” said House Majority Leader Eric Cantor, R-Va., the measure’s sponsor.

“This is not about mom and pop,” said Rep. Sander Levin, D-Mich. “It’s about popping the cork for wealthy taxpayers.”

Eighteen Democrats and 10 Republicans defected from their party’s positions on the bill.

The vote was the second partisan tax showdown in the Capitol this week, prompted by Tuesday’s deadline for filing tax returns to the Internal Revenue Service. On Monday, Democrats failed to push a “Buffett rule” tax on the rich through the Senate, another outcome that was pre-ordained but served political purposes for both sides.

The House GOP measure would let employers with fewer than 500 workers deduct 20 percent of their domestic earnings this year — a calculation that would let businesses show a smaller income before determining the taxes they owe. More than 99 percent of U.S. employers have work forces that size, Census Bureau figures show, but that didn’t stop Republicans from naming the legislation the “Small Business Tax Cut Act.”

Democrats argued that the bill provided the tax cut if a company hired no new employees or even if it fired some. They also complained that it was too generous to wealthy individuals owning small firms and to extremely successful businesses.

One estimate by the nonpartisan Tax Policy Center said 49 percent of its tax breaks would go to taxpayers with income exceeding $1 million. Using a narrower way of calculating earnings, the Joint Committee on Taxation, Congress’ nonpartisan tax analyst, said 18 percent of the benefits would go to those making over $1 million and 57 percent would go to taxpayers earning $250,000 and up.

The White House cited both those arguments when it warned this week that aides would urge Obama to veto the legislation.

Democrats tried taking advantage of the bill’s broad sweep, trying to embarrass Republicans by forcing a vote on language that would have forbidden the tax breaks from going to businesses including pornographers, prostitution, golf clubs that discriminate by race or sex, and companies that send U.S. jobs overseas.