President Obama's decision to send American warplanes into Libya opened the nation's third military theater in the Middle East—and quickly cast the administration onto more battlegrounds at home.

Three days into the first war he's helped to start, Obama finds himself in an increasingly familiar position in relation to the Congress: detached, under fire, and going it largely alone.

American liberals who gravitated to Obama because he was the most plausible anti-war candidate broke sharply with him this weekend for projecting U.S. force into a corner of the world where it's traditionally unwelcome, humanitarian intervention doctrine be damned. Even some congressional Democrats who voted for the Iraq invasion call the Libyan venture "gratuitous" and question Obama's standing. Rep. Dennis Kucinich, D-Ohio, on Monday called the U.S. involvement in Libya an "impeachable offense."

Capitol Hill Republicans, divided for weeks about how to handle Libya, are casting an array of aspersions on Obama's decision; he's been too slow, hasn't adequately consulted Congress, has not developed a clear exit strategy, and not much of an entrance strategy either.

House Speaker John Boehner, R-Ohio, in a statement released during Obama's largely Libya-free speech in Rio de Janeiro on Sunday, hit him over process, saying his administration should "define for the American people, the Congress, and our troops what the mission in Libya is, better explain what America's role is in achieving that mission, and make clear how it will be accomplished.