If President Obama is looking for an excuse to scale back his ambitions in the realm of foreign policy following a lackluster first two years with few successes, the GOP takeover of the House will provide him with a perfect excuse.

The ascent to power of conservative hardliners in key committee chairmanships—likely Ileana Ros-Lehtinen (Florida) at Foreign Affairs, Buck McKeon (California) at Armed Services, Mike Rogers (Michigan) or Mac Thornberry (Texas) at Intelligence—means that a crew of negotiations-hating, counterinsurgency-backing, weapons-system-promoting, Likud-following, START-bashing, Russia-fearing Islamophobes has the reins. Expect great quantities of podium-pounding, scathing speeches about Obama the appeaser/unilateral disarmer, and ersatz hearings calculated to embarrass the White House.

But if Obama wants to ignore all that, for the most part he can, because the House has little or no direct leverage over foreign policy (case in point: House Democrats vs. Bush, 2006–08). Also, since foreign policy played an insignificant role in the GOP electoral tsunami—only a tiny percentage of voters listed it as a major concern—the Republicans can hardly claim a mandate to challenge Obama’s conduct of global affairs. With a revamped national security team—a new national security adviser, a new director of national intelligence and, coming soon, a new defense secretary, a new team of military commanders and possibly a new CIA director—Obama could recast his foreign policy by ending the wars in Afghanistan and Iraq, making a deal with Iran, reducing military spending and improving relations with China and Russia. But if he does, no doubt he’ll have a showdown with the House GOP, refereed on cable news.

Of course, the new House leaders will try to put all sorts of obstacles in Obama’s way. At Foreign Affairs, Ros-Lehtinen and a phalanx of subcommittee chairs will do their utmost. She is a militantly anti-Castro Cuban-American from Miami-Dade County who’ll seek to ratchet up sanctions on Iran and North Korea, halt détente with Cuba and restore the lockstep US-Israeli mindmeld that prevailed during the Bush administration. She’ll seek to slash the foreign aid budget for all countries not called Israel. The Palestinian Authority must drop its conditions for negotiations, recognize Israel as a "Jewish state," clamp down on violent groups and end corruption—or "we should not give it one more dime," she said recently. Since the election, she’s called on Obama to "rethink his ‘reset’ policy with Russia" because of the "brutal nature of the regime," and she said the US-Russia civilian nuclear agreement "should be stopped" because Moscow "continues to undermine US interests in Iran, Venezuela [and] Central Asia." She also railed against the "dangerous behavior" of the presidents of Venezuela, Bolivia, Nicaragua and Ecuador, who pose "tangible risks to the security of our region."

Iran watchers in Washington expect Ros-Lehtinen to try to throw monkey wrenches into the US-Iran talks, and some suggest that House Republicans, led by Ros-Lehtinen and incoming majority leader Eric Cantor, will propose some sort of Iran Liberation Act, parallel to the 1998 Iraq Liberation Act. Like most conservatives, Ros-Lehtinen also strongly opposes Obama’s July 2011 Afghanistan drawdown timetable. And on Iraq, she warned that Washington must "ensure that a strategic defeat does not spring from [the] hard-fought tactical victory" because Obama is "drawing down troop levels quickly—without sufficient focus on the emergence of Iran as the key power broker in that country."

At Armed Services, McKeon is itching for a fight, too. The pugnacious Californian is an old-style pro-military conservative who’s sharply critical of Obama’s Afghan timetable, which he calls "a mistake," adding, "I hope the focus…this time is on winning, not on timetables." Like Ros-Lehtinen, McKeon warns that Obama will lose the war in Iraq "by default" if he pulls troops out in 2011, as planned. He wants a bigger military budget, including more investment in missile defense and an expanded Navy. "Cutting defense spending amidst two wars is a red line for me," he told a neoconservative conference in November. "A defense budget in decline portends an America in decline," he said. And he railed against Obama for talking to America’s adversaries. "The President’s emphasis on engagement has translated into weakness."

McKeon has called for Gen. David Petraeus to testify on Capitol Hill—even, or especially, if the White House prefers to keep the general offstage. McKeon made it clear at the conference that the House GOP would seek an alliance with military commanders in Afghanistan to prevent Obama from enforcing "arbitrary, politically imposed troop caps" on deployments. Still, when I asked McKeon what specifically he could do to block Obama’s policies, he admitted that there isn’t much. "We only have one commander in chief," he acknowledged. "I don’t really see anything that can be done to pull that back."

Ros-Lehtinen’s power is also limited, but she can generate political pressure on Obama. Since the election, she’s suggested that by taking a hardline stance the committee could "help the president be tougher with countries" and that Obama and House Republicans can "play good cop, bad cop." Perhaps the administration will now and then point over its shoulder at Ros-Lehtinen and McKeon and say, "If you don’t deal with me, you’ll end up dealing with them!" But more likely, Obama will find his ability to maneuver constrained, since foreign leaders, friend and foe, will wonder if the president is weakened or even a lame duck.

Some progressives have wondered if the new GOP majority will be filled with so many rogue Tea Party types, including isolationists and libertarians, that antiwar sentiment will grow within the caucus and that many freshmen will try to extend their fervor for budget cuts to the Pentagon. Gordon Adams, a fellow at the Henry L. Stimson Center, says, "It’s going to be real interesting to watch tensions between the Tea Party and regular Republicans." He thinks budget hawks like Paul Ryan, who’ll chair the Budget Committee, might take a scalpel to the military. On the stance her committee will take, Ros-Lehtinen said, "It depends a lot on whether the makeup of our committee will be more Republican-Libertarian or Republican hard line." In the end it’s likely the old guard, whose chieftains will take over the chairmanships, will work hard to minimize the influence of Tea Party rogues and that House Republicans will do their best to huff, and puff, and blow Obama’s house down.