WASHINGTON -- Sen. John McCain, leading a blue-ribbon congressional delegation to Baghdad before Christmas, collected evidence that a "surge" of more U.S. troops is needed in Iraq. But not all his colleagues who accompanied him were convinced. What's more, he will find himself among a dwindling minority inside the Senate Republican caucus when Congress reconvenes this week.

President Bush and McCain, the front-runner for the next presidential nomination, in pressing for a surge of 30,000 more troops, will have trouble finding support from more than 12 out of 49 Republican senators. "It's Alice in Wonderland," Sen. Chuck Hagel, second-ranking Republican on the Foreign Relations Committee, told me in describing the proposed surge. "I'm absolutely opposed to sending any more troops to Iraq. It is folly."

What to do about Iraq poses not only a national policy crisis but profound political problems for the Republican Party. Disenchantment with George W. Bush within the GOP runs deep. Republican leaders around the country, anticipating that the 2006 election disaster would prompt an orderly disengagement from Iraq, are shocked that the president now appears ready to add more troops.

The recent McCain congressional delegation was composed of sophisticated lawmakers who have made many previous visits to Iraq. They do not minimize the severity of sectarian civil war. They left their meeting with Prime Minister Nouri al-Maliki doubting any "sense of urgency" after advising him that he must disarm the militias. They recognize that the national police, corrupt and riddled with radicals, constitutes an unmitigated disaster.

McCain long has called for more troops in Iraq. He was supported within the delegation by his close ally, Sen. Lindsey Graham, and by Sen. Joseph Lieberman, the only Democrat on the delegation (though he now calls himself an "Independent Democrat" after losing the Democratic nomination in Connecticut and being elected with Republican votes). But Sen. John Thune calls his support for the surge "conditional." Sen. Susan Collins returned from Baghdad opposing more troops. Rep. Mark Kirk of Illinois, the only House member on the trip, is described as skeptical.

How big and how long should a surge be? The 7,000 or 8,000 additional troops that were first mentioned now have grown to at least 30,000. Congressional advocates talk privately about a new infusion of manpower ending about halfway through this year. But retired Gen. Jack Keane, who has become a leading advocate of additional troops, wrote in The Washington Post last week: "Increasing troop levels in Baghdad for three to six months would virtually ensure defeat."

I checked with prominent Republicans around the country and found them confused and disturbed about the surge. They incorrectly assumed that the presence of Republican stalwart James Baker as co-chairman of the Iraq Study Group meant it was Bush-inspired (when it really was a bipartisan creation of Congress). Why, they ask, is the president casting aside the commission's recommendations and calling for more troops?

Even in Mississippi, the reddest of red states where Bush's approval rating has just inched above 50 percent, Republicans see no public support for more troops. What is happening inside the president's party is reflected by defection from support for his war policy after November's election by two Republican senators who face an uphill race for re-election in 2008: Gordon Smith of Oregon and Norm Coleman of Minnesota. Coleman announced his opposition to more troops after returning from a trip to Iraq preceding McCain's.

Among Democrats, Lieberman stands alone. Sen. Joseph Biden, as Foreign Relations Committee chairman, leads the rest of the Democrats not only to oppose a surge but to block it. Bush enters a new world of a Democratic majority where the big microphone he talks about is smaller because he must share the stage.

Just as the president is ready to address the nation on Iraq, Biden next week begins three weeks of hearings on the war. On the committee, Biden, Christopher Dodd, John Kerry, Russell Feingold and Barack Obama will compete for intensity in criticizing a troop surge. But on the Republican side of the committee, no less probing scrutiny of Bush's proposals will come from Chuck Hagel.