Speaker John Boehner cautions against sharp troop withdrawal from Afghanistan

House Speaker John Boehner on Wednesday warned against "any precipitous withdrawal" of troops from Afghanistan ahead of President Obama's expected announcement that 30,000 "surge" troops would be coming home by the end of next year.

The nation's highest ranking Republican stressed that he would back the president's decision as long as Obama listens to military and diplomatic officials dedicated to the United States' efforts in Afghanistan.

"If the president listens to the commanders on the ground and our diplomats in the region," Bohener told reporters, "I'll be there to support him."

But Boehner cautioned against an excessively steep withdrawal of troops, citing the extensive United States investments in the region.

"I'm concerned about any precipitous withdrawal of our troops that would jeopardize the success that we've made," he said, without elaborating on what would constitute a precipitous withdrawal.

In prime-time speech to the nation, Obama is expected to say about 5,000 troops will begin coming home this summer with an additional 5,000 troops by the end of this year, sources told CBS News. And about 20,000 more troops are expected to return to the United States by the end of 2012, the sources said. That would still leave about 70,000 troops in Afghanistan -- about twice as many troops as when Obama took office in January 2009.

The Ohio lawmaker noted that "the American people are a bit weary about Afghanistan," adding "you can't blame them" because "a hundred thousand of our young men and women fighting in this desert over there."

A recent CBS News poll found that 64 percent of Americans want the number of troops of Afghanistan reduced, the highest number since CBS News first asked the question in 2009.