WASHINGTON, D.C. — Back from a brief tour of Afghanistan, Sen. Sheldon Whitehouse said Monday that “the baseline” of progress in the U.S. war effort there is better than it might appear from news coverage of rising casualties and the sharp disagreement over how the Obama administration should proceed.

Whitehouse stressed his view that the Taliban are deeply unpopular with the Afghan people, alienating them with brutal tactics comparable to those employed by al-Qaida in parts of Iraq. The Rhode Island Democrat, who sits on the Senate Intelligence Committee, said he was also struck by the continued high levels of “morale and enthusiasm and confidence” of U.S. forces in their mission — even as President Obama and his top advisers continue to debate whether to add tens of thousands of troops to the war effort.

Whitehouse declined to give his view on what the administration should do about the recommendation by the U.S. commander in Afghanistan, Army Gen. Stanley McChrystal, that as many as 40,000 troops be added to the U.S. combat force, as part of a comprehensive counterinsurgency effort.

“Whenever you put more American troops in the field, you will get a better result because they are well trained,” Whitehouse said, and “because they are very good at their mission.” But the senator would venture no further into the debate about whether to raise the combat force beyond the current level of roughly 68,000.

Whitehouse said he wants to avoid “prejudging or forecasting” Mr. Obama’s decision. Whitehouse said he would let Mr. Obama “take his position and explain it before I start reacting to it.”

Whitehouse departed on his tour late last week with Republican Sen. Richard Burr of North Carolina, returning Monday. They met with senior diplomats and military and intelligence officials, including McChrystal and U.S. Ambassador Karl Eikenberry. They met with both contestants in the country’s presidential runoff election, slated for Nov. 7: Afghan President Hamid Karzai and opposition candidate Abdullah Abdullah.

Whitehouse said it was “very important” to the fight against the Taliban that Karzai has agreed to the runoff election against his chief rival. As he explained it, an election that is viewed as fair will help to promote confidence in the government — right down to the level of ordinary citizens under assault by the Taliban.

Whitehouse likened the predicament of typical Afghan villagers to that of “the people in a town run by the mob, where if you have confidence in the government and you’re willing to work with them and report criminals and have trust in the apparatus, you can run the mobsters down.”

But without confidence in the authorities, he said of such citizens, “you feel alone and you stand out, and when the mobsters come to your house and slaughter your family, then you’re not going to take any action against them,” he said. “That principle, spread across the whole country,” explains the importance of a successful election.

But Whitehouse indicated that the United States must seek a balance between “two forces at work” in shaping the Afghan view — recently voiced by Karzai and Abdullah — that more American troops are needed in the fight against the Taliban. On the one hand, he said, the Afghan people “need to have confidence that America will be steadfast and not walk away from what they view as its commitment” to their struggle.

On the other hand, Whitehouse said, “the Afghans are human and like everybody else they’d like to have us to do as much of the lifting as possible.” Thus, he said, the United States must strive “to cultivate their independence from us” — in building up Afghanistan’s own military and police forces, for example — if the alliance against the Taliban is to succeed over the long term.

The analogy to the quelling of al-Qaida forces in western Iraq is only “partially useful,” Whitehouse said. Sunni tribal structures in Iraq were “largely intact” and able to make common cause against al-Qaida with Iraqi government forces and U.S. Marines. But in Afghanistan, he said, 30 years of warfare have eroded tribal cohesion in many parts of the country, so the task of counterinsurgency may be more complicated than in Iraq.

Again and again, Whitehouse said he asked U.S. civilian and military officials, in light of the rising casualties and “all the fuss about electoral fraud” whether anything has happened since his visit earlier this year to cast doubt on the achievability of their mission.

The senator said Americans reassured him repeatedly, “We feel great confidence in what we doing.”

In particular, he said he has been impressed with the “mastery” of U.S. and allied efforts — largely classified intelligence secrets — to identify members of the Taliban and the al-Qaida terrorist organization, “run them down and either detain or disable them.”