One reason why Republicans have taken control of the debate about the stimulus bill is that they're managed to muscle their way onto political television, which influences how other reporters cover the debate. Why do Republican lawmakers outnumber Democratic lawmakers by a ratio of 2 to 1 on the cable news chat shows? There's a very simple reason.
The bookers of the shows look to the White House, not to House Democrats, for the Democratic perspective. If no White House aide can be booked, then they'll quote from the Gibbs briefing. And since the White House's perspective on the stimulus is different, since it's institutional interest is different, they're not going to match the Republican partisan response.
In this way, the presidential megaphone becomes a mild disadvantage. Now -- the White House has started to own the bill. They're putting out more surrogates. Obama's traveling to Florida and Indiana to sell it. The language is getting more aggressive.