* 161,000 jobs added in October vs. est. 175,000
* Unemployment rate falls to 4.9 pct from 5.0 pct
* All three major indexes poised to post weekly losses
* Indexes up: Dow 0.23 pct, S&P 0.40 pct, Nasdaq 0.41 pct (Updates to early afternoon)
By Tanya Agrawal
Nov 4 (Reuters) - The S&P 500 index was on track to snap its eight-day losing streak, its longest since 2008, even as worries over the outcome of the U.S. presidential election continued to weigh on investor sentiment.
Still, the three major indexes looked set to post steep weekly losses.
Investors have been unnerved by signs the U.S. presidential race between Democrat Hillary Clinton and Republican Donald Trump is tightening, after Clinton had until recently been thought to have a clear lead.
The latest Reuters/Ipsos polling showed Clinton, seen as the status quo candidate by markets, maintaining a narrow lead over Trump.
However, several swing states that the Republican challenger must win have shifted from favoring Clinton to toss-ups, offering Trump a possible route to victory.
Nonfarm payrolls increased by 161,000 jobs last month amid gains in construction, healthcare and professional and business services, the Labor Department said.
Unemployment rate fell to 4.9 percent from 5.0 percent and average hourly earnings increased 0.4 percent in October after advancing 0.3 percent in September.
"They were good numbers and pretty much in line with everything we've seen so far," said Paul Nolte, portfolio manager at Kingsview Asset Management in Chicago.
"The market will continue to focus on the polls and probable election results."
Though the U.S. central bank is expected to increase borrowing costs next month, that decision will likely depend on the outcome of Tuesday's election.
Traders are pricing in a 71.5 percent chance for a December rate hike, according to CME Group's FedWatch tool.
The CBOE Volatility Index, a gauge of near-term investor anxiety, fell 2 percent but stayed near a more than four-month high.
At 12:40 p.m. ET (1640 GMT) the Dow Jones industrial average was up 41.09 points, or 0.23 percent, at 17,971.76.
The S&P 500 was up 8.44 points, or 0.4 percent, at 2,097.1.
The Nasdaq Composite was up 20.75 points, or 0.41 percent, at 5,079.16.
Nine of the 11 major S&P 500 sectors were higher, with the healthcare index's 1.03 percent rise leading the gainers.
Regeneron Pharmaceuticals rose 1 percent to $339.45 after its quarterly profit handsomely beat Wall Street estimates.
Humana was up 2.5 percent at $169.94 after the health insurer reported a higher-than-expected quarterly profit.
Starbucks shares were up 2.3 percent at $52.97, a day after the company reported better-than-expected quarterly results. The stock was among those that propped up the S&P and the Nasdaq.
Advancing issues outnumbered decliners on the NYSE by 1,894 to 958. On the Nasdaq, 1,861 issues rose and 823 fell.
The S&P 500 index showed three new 52-week highs and 10 new lows, while the Nasdaq recorded 21 new highs and 110 new lows. (Reporting by Tanya Agrawal; Editing by Anil D'Silva)