US Treasurys pared losses

US 10-YR
US 30-YR

U.S. Treasury yields rose on Wednesday morning, after the Republican party officially took control of the Senate following midterm congressional elections and after ADP reported private-sector job growth for last month. But yields turned flat later after data showed growth in the services sector slowed more than expected in October.

Yields on benchmark 10-year Treasury notes—used to calculate mortgage rates and other consumer loans—were last at 2.339 percent, down 1/32 in price. Yields and prices are inversely related.

The Institute for Supply Management's services index slid for a second month to 57.1 last month, missing analyst forecasts. But service-sector employment hit a fresh nine-year high.

The 30-year bond fell 5/32 in price to yield 3.058 percent in late afternoon.

The new Republican-controlled Congress could help drive a new Asia-Pacific trade pact and make for a more energy friendly environment in Washington, analysts said. It could also be a short-term catalyst for stock markets, unless the outcome is clouded by runoff elections.

Read MoreLive blog:Election 2014—Waking up to a GOP Congress

On the downside, the GOP's victory will likely see ongoing policy stalemate in Washington.

"The Senate seat count is now 52 for the Republicans with two states still to declare and full control of Congress will likely mean some bills, unpopular with the democrats, will be heading to the White House for a signature that obviously won't be forthcoming. That suggests continued policy gridlock in Washington," said Derek Halpenny of the Bank of Tokyo-Mitsubishi in a research note on Wednesday.

Falling oil prices will continue to weigh on Wall Street on Wednesday, with Brent crude touching a four year low and sinking below $82 a barrel before turning up slightly following strong employment figures.

Ahead of Friday's labor market report, the ADP employment report showed the U.S. economy created 230,000 private-sector jobs in October.

Worries about China may weigh on sentiment during the session, after HSBC's China services purchasing managers' index (PMI) for October hit a three-month low. The report follows mixed data on China's manufacturing sector earlier this week.

—Reuters contributed to this report.