the day. And on Thursday, he invited Terry Moran of ABC to spend the day with him for a “Nightline” special.

The all-Obama, all-the-time carpet bombing of the news media represents a strategy by a White House seeking to deploy its most effective asset in service of its goals, none more critical now than health care legislation. But longtime Washington hands warn that saturation coverage can diminish the power of his voice and lose public attention.

About 24.7 million viewers tuned in Wednesday, according to Nielsen ratings, some 4 million fewer than watched his last evening news conference in April and 25 million fewer than saw his first in February. Mr. Obama’s focus on health care produced what Chuck Todd of NBC described as a “snoozer conference,” a line the Republican National Committee happily adopted.

“I’m really perplexed. It’s unbelievable,” said Karen Hughes, Mr. Bush’s White House counselor. “They’ve taken his greatest political asset — his gifts as a communicator — and totally diluted them. It’s been especially notable in the last couple weeks.”