First up for Republicans: Expect this change

Republicans will use their new-found power to take on a variety of issues, but none more so perhaps than tax reform.

Obamacare, the Keystone XL pipeline and immigration also will be high on the radar for a party regaining control of the House and the Senate, but changing the tax code is the most doable in the near term, said Greg Valliere, chief political strategist at Potomac Research Group in Washington, D.C.

"The big story next year, the showcase issue for the Republicans clearly will be tax reform," Valliere said Tuesday while speaking at the Schwab IMPACT conference in Denver. "I imagine that (House Speaker John) Boehner will say this is their top priority."

Republicans for years have been wanting to simplify the voluminous code, particularly with regard to its highest-in-the-world corporate rates, as well as providing incentives for companies to bring home profits that are stashed overseas.

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Meanwhile, Democrats have been looking to stop the swarm of inversions—deals where U.S.-based companies buy another firm and change their domiciles to friendlier tax nations—that they say have been robbing the Treasury of much-needed revenue.

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With support on both sides of the aisle, Valliere sees the issue as the first mark the GOP will make when it assumes control in January.

"The big issue for investors will clearly be the repatriation of earnings that would come back to the U.S. at a very, very low tax rate," he said, adding that multinationals storing cash abroad would be the big winners there.

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In the bigger picture, Valliere said the divide between Democrats and Republicans is not as great as the media portrays. He pointed to a number of legislative accomplishments in 2014—the debt ceiling increase, the farm bill, agreeing to arm Syrian rebels—that he said show hope for getting more done in the next session.

"When you look at the accomplishments this year, this was hardly the year we had in 2013," he said. "The media loves to stir the pot, but I'm not persuaded that Washington is broken."

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