U.S. crude oil prices settled below $50 a barrel on Tuesday, losing more than $5 since last week, as concerns about heating oil supplies and a possible strike action in Nigeria subsided and as traders pocketed profits while the U.S. presidential election got under way.

Light crude for December delivery settled down 51 cents at $49.62 on the New York Mercantile Exchange (search), the lowest settle since Sept. 29 and the first settlement under $50 since Oct. 4. 

Brent crude for December delivery was down 21 cents at $46.85 on the International Petroleum Exchange in London.

While crude prices are still up by more than 70 percent from a year ago, they would need to surpass $90 per barrel to approximate the all-time high, in inflation-adjusted terms, set in 1980.

Alaron Trading Corp. analyst Phil Flynn said the sharp drop in prices from a week ago was due to expectations that the nation's heating oil supply would soon begin to build to more comfortable levels.

"We were a little ahead of ourselves at $55 and we've corrected a little bit," said Flynn. A record Nymex closing price of $55.17 per barrel was reached Oct. 22 and matched four days later.

Even a series of sabotage attacks in Iraq failed to lift prices.

"The news of the Iraqi pipeline is obviously bullish ... but the prospect of a Kerry win is coming into the market now," said broker Paul Goodhew at ABN Amro.

PFC Energy in Washington said a Bush win could stoke nervousness about U.S. policies in the oil-producing Middle East, while Kerry is seen as more likely to work through diplomatic channels.

"Under a Kerry administration we'd likely have a much more interventionist SPR policy," said Jamal Qureshi, market analyst at PFC, late Monday. "And when you look out a bit further, Bush is more likely to be aggressive in the Middle East, particularly in Iran."

The Bush administration continues to add crude to the SPR, the national strategic petroleum reserve (search).

Kerry says he would stop filling the reserve at current prices to keep more crude on the market. That difference is important for a world oil market suffering a shortage of light, sweet crude, which makes up about 40 percent of the SPR.

"A Bush status quo results in somewhat higher oil prices both in the short and the longer term, in my view," said Tim Evans, senior analyst at IFR Energy Services.

Last week, oil prices fell from record closing prices on NYMEX after the Energy Department said U.S. crude supplies had increased by 4 million barrels to 283.4 million barrels — roughly double what Wall Street was expecting.

Distillate stocks, which include heating oil and diesel, however, remain a concern. They have fallen for six consecutive weeks and remain woefully below expected levels prior to the Northern Hemisphere winter.

Prices rose steadily between mid-September and mid-October after Hurricane Ivan (search) caused production outages in the Gulf of Mexico, where more than 26 million barrels of oil output has been lost.

Reuters and the Associated Press contributed to this report.