From the Wall Street Journal:

Republican former Secretary of State Colin Powell’s endorsement of Sen. Barack Obama is the latest sign that the Republican Party’s coalition is fracturing amid the stresses of the campaign….

The endorsement comes after a series of events that have pointed to the fraying of a Republican umbrella that has relied in the past on both moderates and conservatives to bulk up its governing majority.

Late last week, conservative radio talk-show host Michael Smerconish endorsed Sen. Obama, as did conservative columnist Christopher Buckley, the son of National Review founder William F. Buckley. The Chicago Tribune endorsed Sen. Obama last week, the first time the paper has endorsed a Democrat in its 161-year history.

Two Republican senators in the middle of tough re-election fights — Susan Collins of Maine and Norm Coleman of Minnesota — have denounced Sen. McCain’s automated phone calls attacking Sen. Obama. “These kind of tactics have no place in Maine politics,” said Sen. Collins’s spokesman, Kevin Kelley. “Sen. Collins urges the McCain campaign to stop these calls immediately.”

…. In the past weeks, strains have developed on all fronts. Fiscal conservatives, already angered by the growth in government spending and deficits under Mr. Bush, have been incensed by what they see as government intrusion in the markets with the $700 billion Wall Street rescue plan. Sen. McCain voted for the plan, then angered his party’s fiscal-conservative wing further by proposing that the government buy $300 billion in mortgages on homes facing foreclosure.

The Palin pick was intended in part to assuage social conservatives who have long been leery of Sen. McCain. While it seems to have succeeded on that score, it may also have driven off moderate Republicans.

“Whether John wins or loses, the party is going to have to go through a period of introspection, and we’re going to have to regenerate ourselves,” said John Weaver, a former top aide to Sen. McCain.

“The Republican Party is fractured. It is completely, utterly fractured,” said Mark Corallo, a conservative Republican political strategist.