The top U.S. battlefield commander said on Wednesday that President Barack Obama's 30,000-strong troop increase for the Afghan war would make a huge difference, as the White House prepared to sell the new strategy to Congress.

Rising combat deaths and military costs have sapped U.S. public support for the eight-year-old war and Obama's troop increase plan has prompted protests from left-leaning leaders of his Democratic Party ahead of congressional elections next year.

Within hours of Obama's speech announcing the extra troops -- delivered as Wednesday dawned in Afghanistan -- top U.S. and NATO commander General Stanley McChrystal set off on a battlefield tour to rally his forces.

Paraphrasing Winston Churchill in a rousing speech by videophone to his commanders, McChrystal called Obama's pledge of reinforcements the end of the beginning of the war.

But the Taliban, in a statement issued by email, said the increase would only increase their resolve.

This strategy by the enemy will not benefit them, it said.

McChrystal told his commanders the additional forces would at last give them the troops they need to speed up the training of Afghan security forces and protect towns and villages.

Training Afghan troops was now their main effort, he said.

At the end of the day, the success of this operation will be determined in the minds of the Afghan people, he said.

It's not the number of people you kill; it's the number of people you convince. It's the number of people that don't get killed. It's the number of houses that are not destroyed. It's the number of children that do get to go to school.

Asked later if he was getting enough new troops, he told reporters: I think it is going to make a huge difference. I think we'll be in great shape.

Top Obama administration officials were due in Congress later on Wednesday where they can expect a grilling from Democrats dubious of escalating the war, and Republicans suspicious of Obama's call for an 18-month timeline to begin withdrawing.

In his televised speech on Tuesday, Obama said the goal of raising U.S. troop levels to nearly 100,000 was to step up the battle against the Taliban, secure key centers and train Afghan forces so they can take over, allowing for a U.S. withdrawal.

We always wanted to take over the responsibility for the destiny of our nation, Afghan Defense Minister Gen. Abdul Rahim Wardak told reporters, adding that Obama's speech confirmed that the U.S. wants to help them do that.

We just asked the international community to equip us quickly, to train us quickly, so that we can fulfill our historic responsibility.

Allies were also expected to send more soldiers, with Obama saying the common security of the world was at stake.

British Prime Minister Gordon Brown urged coalition countries to back Obama's initiative. French President Nicolas Sarkozy welcomed the plans, but did not commit France to following suit. Poland said it might send 600 troops to boost its contingent of 2,000.

SHORTER TIMELINE

There was no initial word from President Hamid Karzai, whose relations with the Obama administration are strained amid a re-election which involved widespread voter fraud.

But after meeting Karzai, McChrystal said the Afghan president backed the plan. It was really positive. The president was very upbeat, very resolute.

Karzai is due to announce the makeup of his new government in coming days, and Washington says it is watching closely for signs he will combat corruption and appoint competent ministers.

Obama's pledge to start bringing U.S. troops home in 2011, provided conditions on the ground allow it, may help him contain rebellion among Democrats but drew swift condemnation from Republicans, who argue that setting withdrawal timelines emboldens the Taliban and undermines support for U.S.-backed governments in Afghanistan and Pakistan.

Congressional committees scheduled hearings on Wednesday and Thursday to review the revised strategy, estimated to cost $30 billion this fiscal year. Obama has the authority to send the soldiers, but Congress must approve the cost.

Secretary of State Hillary Clinton, Defense Secretary Robert Gates and the chairman of the Joint Chiefs of Staff, Admiral Mike Mullen, are scheduled to appear before Congress.

McChrystal, who had recommended sending 40,000 troops, will testify next week.

TROOP MOVES FROM JANUARY

Major U.S. troop movements are likely to begin in January and all 30,000 should be in place by the end of August, far faster than planners had earlier suggested but in line with McChrystal's request for reinforcements before the summer fighting season.

Other NATO members are expected to commit between 5,000 and 7,000 additional troops, although some of them are already deployed as part of the alliance's 42,000-strong contingent.

Marking a major shift in U.S. strategy, McChrystal said the vast majority of the new combat troops would be fielded in partnership with Afghan units, a counter-insurgency mentoring tactic he said had not been fully possible in the past because the Afghan army and police were too small.

In his speech, Obama also focused on Pakistan, saying a cancer had taken root in its border region with Afghanistan and promised U.S. help to end it. Some officials in Islamabad fear the U.S. surge in Afghanistan will further destabilize their country.

(Additional reporting by Phil Stewart in WASHINGTON; Sayed Salahuddin in KABUL and Zeeshan Haider, Augustine Anthony and Michael Georgy in ISLAMABAD; Editing by David Fox) .