Snow replaces Scott McClellan, who stepped down in a White House makeover intended to re-energize Mr. Bush's presidency and lift the president's record-low approval ratings. McClellan has served as President Bush's chief spokesman — the most prominent public figure in the White House after Mr. Bush — for nearly three years.
"I am confident Tony Snow will be a great addition to the White House staff," Mr. Bush said.
2"My job is to make decisions and his job is to help explain those decisions to the press corps and the American people," Mr. Bush said, with Snow and McClellan at his side in the White House briefing room.
McClellan said Snow will become press secretary May 8 although he is not expected to start briefing that soon. McClellan expects some "overlap" before Snow takes over, reports CBS News correspondent Peter Maer.
Despite the rumors swirling over his appointment, Snow wasn't completely sold. Before taking the job he wanted to negotiate unlimited access, a guarantee that he'll play a role in both policy debates and the hiring of White House communications staff, reports CBS News correspondent Susan Roberts.
Snow, a Fox News commentator, has written and spoken frequently about the current president — although not always in a complimentary way.
The Center for American Progress, a liberal think tank, circulated unflattering observations by Snow about Mr. Bush.
"His (Bush's) wavering conservatism has become an active concern among Republicans, who wish he would stop cowering under the bed and start fighting back against the likes of Harry Reid, Nancy Pelosi and Joe Wilson," Snow wrote last November after Republicans failed to win the governor's race in Virginia. "The newly passive George Bush has become something of an embarrassment."
Asked about some of Snow's past critical comments of the President McClellan said, "He has strong views.
"That's a good thing, but now he represents the President and his agenda," McClellan said.
Last month, Snow wrote that President Bush and the Republican Congress have "lost control of the federal budget and cannot resist the temptation to stop raiding the public fisc. (treasury)"
Snow, in an Associated Press interview on Tuesday, said: "It's public record. I've written some critical stuff. When you're a columnist, you're going to criticize and you're going to praise."
One factor in the timing of Snow's decision is said to be a battle last year with cancer, involving six months of chemotherapy. He had a CAT scan last week and is said to have delayed a decision on the White House job until he had a chance to consult with his doctors.
Snow is the host of the "Tony Snow Show" on Fox News Radio and "Weekend Live with Tony Snow" on the Fox News Channel. He served in the administration of President George H.W. Bush, as White House speechwriting director, and later on as a deputy assistant to the president for media affairs.
Brit Hume, Fox's Washington managing editor, told the Washington Post that he was "a little surprised" that Snow would forgo a leave a brand new radio show to take on one of Washington's most demanding jobs.
"I think he's excited by the idea of being on the inside," Hume told the Washington Post. "He believes he will be at the table when decisions are made. For someone of his bent, that's too good to pass up."