Former Massachusetts Gov. Mitt Romney (R) announced on Tuesday that he opposes the tax-cut deal making its way through Congress.

Romney, one of the top contenders for the 2012 GOP presidential nomination, said that President Obama's deal on tax cuts with congressional Republicans wouldn't add enough certainty to a struggling economy.

"Given the unambiguous message that the American people sent to Washington in November, it is difficult to understand how our political leaders could have reached such a disappointing agreement," Romney wrote in an op-ed for USA Today. "The new, more conservative Congress should reach a better solution."

Romney is arguably the highest-profile Republican to oppose the deal, which extends all expiring tax cuts for two years in exchange for the extension of unemployment benefits and some middle-class tax breaks.

The former Massachusetts governor is expected to mount one of the top campaigns for the Republican presidential nomination in 2012. Most other potential Republican presidential candidates have backed the deal Obama struck with congressional Republicans.

"On balance, we've got to make sure those taxes don't go up," Minnesota Gov. Tim Pawlenty (R), another 2012 contender, said in support of the deal on Iowa radio.

Two other Republican contenders — former Alaska Gov. Sarah Palin and Sen. Jim DeMint (S.C.) — have sharply criticized the deal. Romney echoed their worries that the tax deal, with its new unemployment spending, would add too much to the deficit.

"What some are calling a grand compromise is not grand at all, except in its price tag," Romney wrote. "The total package will cost nearly $1 trillion, resulting in substantial new borrowing at a time when we are already drowning in red ink."

The decision by Romney to oppose the deal also ramps up pressure on congressional Republicans. Only five of 42 Republican senators voted against the deal on Monday. The House is expected to vote later this week.