The Republicans are turning decidedly dovish, and using the issue of war and peace against President Obama. Bravo to them.

On Monday, I blogged about the emergence of Jon Huntsman, who’s announcing for president next week, and Senator Bob Corker, a top-ranking Republican from Tennessee on the Senate Foreign Relations Committee, as antiwar voices. On Tuesday, I blogged about the surprising and welcome absence of bellicose rhetoric at the GOP debate in New Hampshire, where Mitt Romney, Newt Gingrich and Michelle Bachmann, along with Ron Paul, talked about the need to bring the troops home quickly and stop the war in Libya.

Now, John Boehner, the speaker of the House, is warning that he’ll challenge Obama on the War Powers Act over the illegal and reckless US war against Libya. To be sure, the Act is a joke, and it’s been ignored by every president since it was enacted. But, giving it his best shot, Boehner said:

“Given the mission you have ordered to the US Armed Forces with respect to Libya and the text of the War Powers Resolution, the House is left to conclude that you have made one of two determinations: either you have concluded the War Powers Resolution does not apply to the mission in Libya, or you have determined the War Powers Resolution is contrary to the Constitution.”

Boehner, a hack politician, couldn’t care less about war and peace in Libya, but he’s reflecting a groundswell of grassroots Republican opinion that the wars in Libya, Iraq, Afghanistan and elsewhere are too expensive, contrary to US national interest, and/or unwinnable.

Meanwhile, a group of Republicans in the House has joined Representative Dennis Kucinich in a court challenge to the war in Libya. The lawsuit is signed by Representatives Dennis Kucinich (D-OH), Walter Jones (R-NC), Howard Coble (R-NC), John Duncan (R-TN), Roscoe Bartlett (R-MD), John Conyers (D-MI) Ron Paul (R-TX), Michael Capuano (D-MA), Tim Johnson (R-IL) and Dan Burton (R-IN).

According to Kucinich’s office, the group filed suit today in federal court “against President Barack Obama to challenge the commitment of the United States to war in Libya absent the required constitutional legal authority.”

The New York Times, on page 1, took note of the GOP debate on Monday night, suggesting that Republicans were abandoning the neoconservative hawks in droves. It noted:

“The shift, while incremental so far, appears to mark a separation from a post-Sept. 11 posture in which Republicans were largely united in supporting an aggressive use of American power around the world.”

And the Times quoted John Ullyot, “a former Marine intelligence officer who served as a Republican spokesman on the Senate Armed Services Committee during the height of the Iraq and Afghanistan wars,” saying:

“Republicans clearly sense fatigue among voters with our decade-long effort in Afghanistan, particularly after the killing of Bin Laden and the lack of a reliable partner. There is no stampede yet, but more Republicans are willing to raise tougher questions when it comes to committing our forces and sustaining long-term and costly engagements.”

And Jackson Diehl, the uber-hawkish editor of the Washington Post, notes on his blog that the GOP is waxing dovish, though Diehl churlishly calls it “isolationist,” adding:

“All in all this first Republican debate offered a striking change of tone for a party that a decade ago was dominated, in foreign policy, by the neoconservative movement, which favored (and still does) aggressive American intervention abroad. It also differed sharply from the last Republican presidential nominee, Sen. John McCain (R-Az.), who has been one of the strongest advocates of military action in Libya. You would expect Republicans to attack Obama’s foreign policy performance, particularly in the Middle East. But it will be remarkable if the criticism continues to come from the anti-intervention left, rather than the hawkish right.”

Stay tuned.