Updated

American voters are more likely to think President Obama’s decision to remove a portion of U.S. troops from Afghanistan was motivated by politics rather than economics or national security, and few believe U.S. goals have been achieved there. Even so, most voters approve of his plan.

By a decisive 74-20 percent margin, voters approve of the president’s decision to remove roughly 30,000 U.S. troops from Afghanistan by September 2012, according to a Fox News poll released Wednesday.

Almost all Democrats (92 percent), about three-quarters of independents (74 percent) and over half of Republicans (55 percent) approve of the president’s plan. Women (77 percent) are more likely than men (71 percent) to approve.

Most of the one in five voters who disapprove of the decision think U.S. troops should stay longer.

Click here for the poll results.

U.S. and coalition troops invaded Afghanistan less than a month after the September 11 attacks that were ordered by Al Qaeda leader Usama bin Laden. Bin Laden was killed in Pakistan by U.S. forces on May 2, but Taliban insurgents remain a threat to the democratically-elected government.

In announcing his decision last Wednesday the president said that, “we are meeting our goals.” Few voters -- 15 percent -- agree with that assessment. Nearly two-thirds (64 percent) think that while progress has been made, the Afghanistan mission has not yet been accomplished -- a view that spans the political spectrum. Majorities of Republicans (70 percent), Democrats (63 percent) and independents (54 percent) call the mission “incomplete.”

In addition, 15 percent of voters say the mission in Afghanistan failed. Independents (22 percent) are almost twice as likely as Democrats (12 percent) to say it failed.

On Tuesday, the Taliban took credit for a suicide bombing attack on the Intercontinental Hotel in the Afghan capital Kabul.

Even though most voters approve of the president’s decision to withdraw troops, many more voters think the decision was based on political rather than economic or security reasons.

Nearly half (48 percent) think the main reason was the upcoming 2012 presidential election. About one voter in four thinks the reason behind the drawdown was the U.S. can’t afford the war (24 percent). The smallest number -- 17 percent -- says the president’s main reason was he believes most U.S. goals have been achieved.

Democrats are alone in saying the top factor in the president’s decision was the economy. Republicans and independents are most likely to say it was a political decision.

The United States currently has about 100,000 troops in Afghanistan.

As a candidate, Obama called Afghanistan a "war of necessity" and made clear his commitment to the U.S. action there. During a Senate Committee meeting Thursday, Gen. David Petraeus, currently the top U.S. commander in Afghanistan, said the decision to remove troops over the next year was “more aggressive” than had been recommended by his team.

A 59-percent majority of voters say they trust Petraeus more than Obama to decide next steps in Afghanistan. That’s twice as many as say they trust Obama more (27 percent).

Eighty-six percent of Republicans say they trust Petraeus more to decide how to proceed, as do over half of independents (58 percent).

Among Democrats, 49 percent say they trust the president more and 35 percent Petraeus.

Petraeus, who has been picked to lead the CIA, made the comment about the president’s decision during a Senate hearing on his nomination. Current CIA director Leon Panetta is moving to the defense department to take over for retiring Sec. Robert Gates. The Senate Intelligence Committee unanimously voted Tuesday to confirm Petraeus as CIA director.

Overall Confidence in Leaders

Majorities of voters have a great deal or some confidence in Obama (58 percent) and Petraeus (65 percent). For comparison, less than half of voters have at least some confidence in House Speaker John Boehner (46 percent) and presidential hopeful and former Mass. Gov. Mitt Romney (43 percent).

Meanwhile, Secretary of State Hillary Clinton bests them all: 72 percent of voters have confidence in her (33 percent “a great deal” and 39 percent “some”).

About one voter in four says they have no confidence at all in the president (26 percent). That’s more than three times as many as say they have no confidence in Petraeus (7 percent). Some 19 percent are unable to rate Petraeus.

The Fox News poll is based on landline and cell phone interviews with 912 randomly chosen registered voters nationwide and was conducted under the joint direction of Anderson Robbins Research (D) and Shaw & Company Research (R) from June 26 to June 28. For the total sample, it has a margin of sampling error of plus or minus 3 percentage points.