Several Democratic senators are threatening to hold up valuable arms deals with Middle Eastern countries if OPEC members don't increase oil production to help ease the cost of gasoline.

With gasoline prices topping $3.50 a gallon nationwide, several senators on Thursday called on President Bush to exert pressure on members of the Organization of Petroleum Exporting Countries to boost oil supplies.

Sen. Chuck Schumer of New York led the group protesting what he described as a manipulation of supplies to drive up prices. He said the senators are not yet introducing a resolution that would prevent any arms deal from being passed in the Senate Foreign Relations Committee.

But lawmakers are already eyeing a major deal to provide laser-guided missiles that are shot from planes, Schumer said, and unless they see some reciprocity in the relationship between the U.S. and those nations, it and other deals are ripe for refusal by the Senate.

Democratic Sen. Byron Dorgan of North Dakota added that the U.S. is "very dependent on foreign sources of oil," something he said oil-producing nations fail to appreciate. He noted that Saudi Arabia was producing 9 million barrels a day in 2005, but by 2008 the Saudis had reduced production to 8.2 million barrels.

The Saudis "then say, 'Oh by the way, we need your help on weapons programs,'" Dorgan said. "That is not the way a partnership works."

Sen. Bernie Sanders, I-Vt., said the frustration lawmakers feel comes from the sense that nations like Saudi Arabia and Kuwait don't appreciate the support they've received from the U.S. in the past. As an example, he cited the American effort in 1991 to protect those countries from Saddam Hussein.

"The truth of the matter is that OPEC itself is a cartel which is in violation of World Trade Organization rules, which presumably require competition and free enterprise. The function of OPEC is to limit oil supplies.

"So the demand is right now, President Bush, tell your friends in OPEC, tell your friends in Saudi Arabia that they've got to significantly increase oil production to drive down prices in this country.

"If they are not prepared to extend the hand of friendship to the United States, then we've got to think about an appropriate response, which certainly includes making sure they do not get weapons that we have supplied them with," Sanders said.

Sen. Bob Casey, D-Pa., noted that Saudi Arabia has also failed to deliver billions of dollars in pledged assistance to Iraq, expecting the United States to shoulder the burden without any help in return.

AAA said a gallon of regular gas averaged $3.56 on Thursday, an increase of 3 cents from a day earlier. Oil was selling at over $118 a barrel in Asian trading overnight.

Several analysts say the rise and fall of oil prices is a response to the value of the weak dollar. The weaker the dollar, they say, the more oil becomes a commodity to be used as a hedge against inflation. The dollar rose overnight in Asia after making up some ground against the euro.

OPEC's chief said he doubts supply is affecting prices.

"Oil prices, there is a common understanding that has nothing to do with supply and demand," OPEC Secretary-General Abdullah el al-Badri said Sunday during an energy conference in Rome. He added that OPEC would increase supply if that appeared to be the cause of the spiking oil prices.

The Associated Press contributed to this report.