Factbox: Democrats gain one U.S. Senate seat so far, Republicans hold House

(Reuters) - Majority control of the U.S. Senate was up for grabs in Tuesday's election, with 29 out of 34 results called by major TV networks, including one pickup by the Democrats in Illinois. A handful of extremely tight Senate races remained too close to call, while the networks declared that Republicans, as expected, retained their majority in the House of Representatives. The outcomes in both chambers will help determine how hard it will be for either Democrat Hillary Clinton or Republican Donald Trump to get things done as president. The following are facts on the stakes and races to watch: U.S. Senate, 100 seats. Senators serve six-year terms. A third of the Senate is up for re-election every two years. Procedural rules in the Senate mean 60 votes are needed to advance major initiatives. Republicans entered the election with 54 seats, led by Kentucky's Mitch McConnell, versus the Democrats' 44 seats and two independent seats. The Democrats' leader in the next Senate is expected to be New York's Chuck Schumer. The Republicans this year were defending 24 seats; the Democrats, 10. U.S. House, 435 seats Members of the House serve two-year terms and all are up for re-election every two years. To advance most bills in the House, 218 votes or more are needed. Republicans went into the elections holding 246 seats to the Democrats' 186. There were three vacancies. The Republican leader is Speaker Paul Ryan of Wisconsin; the Democrats' leader is Nancy Pelosi of California. To win a majority, Democrats needed to gain 30 seats. Senate races, with projected results where available: Alabama - Senate Banking Committee Chairman Richard Shelby, as expected, won a sixth term, defeating Democrat Ron Crumpton. Arizona - Veteran Republican Senator John McCain, 80, defeated Democratic U.S. Representative Ann Kirkpatrick, 66. Arkansas - Republican Senator John Boozman beat Democrat Conner Eldridge. California - State Attorney General Kamala Harris, a Democrat, won the seat held by retiring Democratic Senator Barbara Boxer. Harris defeated fellow Democrat Loretta Sanchez. Colorado - Democratic Senator Michael Bennet won a third term, turning back a challenge from Republican Darryl Glenn. Connecticut - Democratic Senator Richard Blumenthal won a second term, defeating Republican Dan Carter. Florida - Incumbent Republican Marco Rubio, the failed presidential contender, defeated Democratic Representative Patrick Murphy. Georgia - Republican Senator Johnny Isakson won his race against Democrat Jim Barksdale. Idaho: Republican Senator Mike Crapo defeated Democrat Jerry Sturgill. Indiana - Democrat Evan Bayh, 60, failed in his bid to recapture his Senate seat, defeated by Republican Representative Todd Young, 44. Illinois - Democratic Representative Tammy Duckworth unseated Republican Senator Mark Kirk. Duckworth, 48, is a double-amputee Iraq War veteran. Kirk, 57, suffered a stroke that sidelined him for much of 2012. Iowa - Republican Senate Judiciary Committee Chairman Chuck Grassley, 83, won a seventh term, defeating Democrat Patty Judge. Kansas - Republican Senator Jerry Moran won a second term, defeating Democrat Patrick Wiesner. Kentucky - Republican Senator Rand Paul won a second term against Democrat Jim Gray. Paul unsuccessfully ran for president earlier this year. Louisiana - A runoff election will be held on Dec. 10 to decide whether Republican John Kennedy or Democrat Foster Campbell replaces Republican Senator David Vitter who is retiring. Maryland - Democratic Representative Chris Van Hollen will replace retiring Senator Barbara Mikulski. Van Hollen defeated Republican Kathy Szeliga. Missouri - Republican Senator Roy Blunt, 66, faces a stiff challenge from Democrat Jason Kander, 35, a veteran of the Afghanistan war who is now Missouri's secretary of state. Nevada - Catherine Cortez Masto, 52, a former Democratic state attorney general, beat Republican Representative Joe Heck, 55, in a battle to replace retiring Democratic Senator Harry Reid. New Hampshire - Democratic Governor Maggie Hassan, 58, is trying to oust Senator Kelly Ayotte, a 48-year-old Republican. New York - Senator Chuck Schumer, who is expected to become the next Senate Democratic leader, defeated Republican Wendy Long in the heavily Democratic state. North Carolina - Republican Senator Richard Burr, 60, won re-election against Democrat Deborah Ross, 53, a former state legislator. North Dakota - Republican Senator John Hoeven won a second term, defeating Democrat Eliot Glassheim. Ohio - Republican Rob Portman, 60, defeated Democratic challenger Ted Strickland, 75, a former governor. Portman initially endorsed Trump, but later withdrew that and pointedly refused to appear with Trump or talk about him. Oklahoma - Senator James Lankford won a second term, defeating Democrat Mike Workman in this overwhelmingly Republican state. Oregon - Senator Ron Wyden, the senior Democrat on the Senate Finance Committee, defeated Republican Mark Callahan. Pennsylvania - Republican Senator Patrick Toomey, 54, faces Democrat Katie McGinty, 53, in the most expensive U.S. Senate contest in the country. Toomey has refused to take a position on Trump. An Oct. 30-Nov. 4 poll by the Allentown Morning Call and Muhlenberg College had Toomey with a small lead, 43 percent to 42 percent. South Carolina - Senator Tim Scott, the only African-American Republican in the Senate, beat Democrat Thomas Dixon. South Dakota - Senator John Thune, a member of the Senate Republican leadership, won a third term, defeating Democrat Jay Williams. Utah - Conservative Republican Senator Mike Lee, in this heavily Republican state, won against Democrat Misty Snow. Vermont - Senator Patrick Leahy, the longest-serving Democrat in the Senate, beat Republican Scott Milne. Washington - As expected, Senator Patty Murray, a member of the Senate Democratic leadership, defeated Republican Chris Vance. Wisconsin - Democrat Russ Feingold, 63, failed to oust Republican Ron Johnson, 61, according to projections. Johnson unseated Feingold in 2010 and was seen as one of the most vulnerable Republicans going into the 2016 campaign. (Reporting by Susan Cornwell, Andy Sullivan and Richard Cowan; Editing by Kevin Drawbaugh and Peter Cooney)