Factbox: Too close to call - U.S. federal, state elections still in flux

(Reuters) - Democrats took control of the U.S. House of Representatives in the Nov. 6 elections and Republicans held onto a majority in the U.S. Senate, but more than a dozen races remain undecided nearly a week later.

The outcomes of two Senate races, 13 House seats and two governorships had yet to be settled on Monday.

The results of Arizona's U.S. Senate race became clear on Monday, when Democratic candidate Kyrsten Sinema declared victory and Republican candidate Martha McSally conceded after multiple media outlets called the race for Sinema.

Florida ordered a recount in the race where Democratic Senator Bill Nelson trailed his Republican challenger, Florida Governor Rick Scott. Florida also ordered a recount for its gubernatorial race, while the winner of the governor's race in Georgia remained uncertain, with a December runoff still possible.

In one of Mississippi's U.S. Senate races, Republican Senator Cindy Hyde-Smith and her Democratic challenger, Mike Espy, will contest a runoff on Nov. 27 after neither won a majority.

Vote tallies continue to trickle in for the 13 U.S. House races that appear too close to call, and there is no consensus among media outlets and data provider DDHQ that a victor has emerged.

Democrats held narrow leads in eight of those races, according to unfinished tallies compiled by DDHQ.

Democrats have so far gained a net 29 House seats. Even if they pick up more seats in the Senate or House, the outcomes of the undecided elections will not change the overall balance of power in either chamber.

(Reporting by Tim Ahmann and Jason Lange in Washington; Editing by Colleen Jenkins and Peter Cooney)