WASHINGTON — Democrats want to push tax cuts through the Senate for companies that hire new workers, give raises or buy major new equipment this year.

With neither party eager to let the other claim campaign-season victories, the ultimate fate of the roughly $29 billion legislation seems dubious. Debate was to begin Tuesday, though it was possible Republicans would use procedural blockades to quickly derail the measure.

The legislation would grant tax credits — which are subtracted from a company's tax bill — equal to 10 percent of the amount its 2012 payroll exceeds the salaries it paid in 2011. The maximum credit would be $500,000, a figure that would disproportionately help smaller businesses.