U.S President urges Republicans To Work With Him As Control of U.S. Congress Unclear.

ALPHARETTA, Ga./PHOENIX, Ariz., Nov 9 (Reuters) - U.S. Senate control hung in the balance while Republicans moved closer to securing a majority in the House of Representatives on Wednesday, a day after Democrats outperformed expectations and avoided a Republican "red wave" in midterm elections.

The Senate contests in Nevada and Arizona, where Democratic incumbents were seeking to hold off Republican challengers, were as yet undecided, with thousands of uncounted ballots that could take days to tally.

If the parties split those races, the Senate's fate would come down to a Georgia runoff election for the second time in two years, after Edison Research projected neither Democratic incumbent Raphael Warnock nor Republican Herschel Walker would reach the 50% necessary to avoid a Dec. 6 one-on-one rematch.

Republicans were closing in on the 218 seats needed to wrest control of the House from Democrats, with 208 now in their column, Edison Research projected. But 23 of the 53 most competitive races, based on a Reuters analysis of the leading nonpartisan forecasters, were still pending as of Wednesday afternoon, raising the prospect that the final outcome may not be known for some time.