WASHINGTON (AP) — Hospital associations, labor groups, tea party supporters and die-hard liberals are plunging into the debt battle between President Barack Obama and Congress as it whirls toward a final showdown. Yet many lobbyists concede that the fight is so intensely political and mutates so fast that it's been hard to make much of an impact.

That uncertainty — coupled with a widespread expectation that lawmakers will ultimately agree on a debt limit extension anyway — help explain why lobbying on the issue has been relatively low key. That's a stark contrast to the high-profile lobbying wars of 2009 and 2010 over Obama's health care and financial regulation overhauls.

"We thought about whether we should be doing more paid media," or advertising, said executive director Justin Ruben of the liberal MoveOn.org, which is mobilizing its 5 million members to tell Congress that they oppose potential cuts in benefit programs like Medicare. "The main thing holding us back is the speed with which events are moving."