By Rodrigo Campos and Ryan Vlastelica

NEW YORK (Reuters) - While the Republican Party won't assume its Senate majority until January, U.S. stock investors are already betting the new congressional makeup could lead to faster action on pipelines and trade agreements, sending energy shares higher on Wednesday.

Wall Street rose broadly in its first session after midterm elections, but energy and medical device companies - two sectors that could see a more direct impact from legislative measures - had outsized moves.

Part of the broader market's move came on relief that the Senate majority party was not in doubt; investors had been concerned some close races would be forced into run-offs, an outcome that could have delayed knowing who would control Congress's upper chamber for weeks.

"It had looked like some of the races would be very close and that we might not know who controlled the Senate, but in the end, the results were pretty decisive," said John Carey, portfolio manager at Pioneer Investment Management in Boston. "That's good news for the industries that had been subject to regulatory issues."

The S&P Energy sector (.SPNY) rose 1.5 percent on hopes Republican control of the Senate will lead to reforms in crude and natural gas export laws, as well as motivate the Obama administration to include those energy exports in new, or broader, trade agreements.

TransCanada Corp (TRP.N) had one of the biggest election-related bounces, jumping 2.4 percent to $49.51 on the New York Stock Exchange. The Canadian company's Keystone XL pipeline project may find easier approval with a Republican-led Senate.

The jump in energy was partially fueled by its recent weakness. The group is the sole industry group in the S&P 500 with negative year-to-date returns, pressured by a massive drop in the price of crude oil.

Other issues that may also find traction under Republicans include a potential repeal of the medical-device tax that is part of the Affordable Care Act, which could benefit the healthcare technology sector. Medical device maker Stryker (SYK.N) rose 0.3 percent to $87.91, roughly in line with the broader market, while Medtronic Inc (MDT.N) added 1.3 percent to $68.87.

On the downside, casino stocks were sharply weaker. MGM Resorts (MGM.N) sank 3.8 percent to $21.48, while Las Vegas Sands (LVS.N) was off 2.7 percent at $58.07. Some had speculated that Republicans could try to slow adoption of online gaming, which was seen as boosting the group.

Beyond that, with Republicans controlling both houses of Congress and a Democrat in the White House, political analysts expect more of the gridlock that has characterized most of the six years of President Barack Obama's tenure.

Republicans also strengthened their grip on the U.S. House of Representatives and when the new Congress takes over in January, Republicans will be in charge of both chambers for the first time since elections in 2006.

While the Republicans don't have a large enough majority in either the House of Senate to override a filibuster or veto, it is possible an emboldened party will attempt to force budget cuts and consider another battle over the debt ceiling in 2015.

Such actions could sap market confidence, as occurred in recent such battles, most notably in 2011, when a budget fight led to the first-ever downgrade of the U.S. credit rating.

"Republicans who want to make a run for control of the executive branch in 2016 will likely strike a tone of compromise," said Jacobsen, but "those on the fringe will likely look to turn the showdown into a shutdown."

History shows a bullish bias in stocks after midterm elections. Since 1928, the S&P 500 has posted a median return of 7 percent in the 90 days after a midterm, with returns positive 86 percent of the time, according to Barclays.





(Editing by Steve Orlofsky, Toby Chopra and Alan Crosby)