President Bush has laid out an ambitious second-term agenda in an effort to drastically change America's social contract, but overreaching has long been the bane of Presidents, from FDR to LBJ, Richard Nixon to Ronald Reagan.

Josh Marshall has already documented the many instances of GOP defections on Social Security privatization. Now The New York Times sets to the task of examining attacks by some Republicans on two of the Presidents other initatives: Clean-Air and Immigration. To begin, Michael Janofsky writes "Climate Debate Threatens Republican Clean-Air Bill":

The Congressional battle over how to reduce air pollution from power plants began anew on Wednesday with consideration of the approach most favored by the White House.

But after three hours of testimony on that initiative, the Clear Skies Act of 2005, it was obvious that nothing had diminished the concerns that scuttled an earlier version of the legislation. Indeed, one co-sponsor conceded that without major compromises, the new bill was most likely doomed.

"If everybody's hunkered down, it's the same old story we've had for the last five or six years," said the lawmaker, Senator George V. Voinovich, Republican of Ohio. "Then it's goodbye."

Though the Republicans increased their numbers in both houses of Congress, they are far from possessing overwhelming majorities. As a result, even a handful of fainthearted members of their caucus can derail even the most well-planned political moves. Such is the case with reshaping the Clean Air Act.

The GOP as a whole might be wedded to corporations and thus stringently opposed to regulation, but individual members -- including conservatives the likes John McCain, Judd Gregg and John Sununu -- are staunch conservationists. As a result, it might be impossible for the President to ram through another measure to curtail environmental law.

On another issue, the President could see defections from the right rather than the left. In Thursday's paper, The Times' David D. Kirkpatrick writes about George W. Bush's immigration woes.

The battle within the Republican Party over immigration policy was joined Wednesday as President Bush vigorously promoted his proposal for a guest worker program and conservatives in Congress introduced an alternative proposal to tighten immigration restrictions.

At a news conference, President Bush said again that he considered his guest worker proposal "a priority" even though Senate Republicans left it off their list of top goals. "A program that enables people to come into our country in a legal way to work for a period of time, for jobs that Americans won't do, will help make it easier for us to secure our borders," Mr. Bush said, adding: "I know there is a compassionate, humane way to deal with this issue. I want to remind people that family values do not end at the Rio Grande border."

Party conservatives, however, have strenuously opposed a guest worker plan since Mr. Bush introduced the idea in 2001, even staging a losing revolt over its inclusion in the party platform at the 2004 Republican convention. Many conservatives call the president's ideas "amnesty" - a term Mr. Bush disputes - because his plan includes ways for currently illegal immigrants to obtain temporary worker permits.

Bush won in 2004 on the basis of overwhelming conservative support, and his approval rating is in fact still buoyed by the right. Nonetheless, in order to govern he must at least make token gestures to the center, such as this immigration initiative. This puts him in an extremely difficult situation. George W. Bush might be one of the most deft politicians in the nation -- indeed only Bill Clinton more of a knack for connecting with the multitude of Americans -- but on these two issues, even he might not succeed.