WASHINGTON — Colin Powell, who only a decade ago was being discussed as a possible Republican presidential nominee and who more recently served as President Bush’s first secretary of state, is advising a Democratic presidential candidate, Senator Obama of Illinois.

Appearing on NBC’s “Meet the Press” yesterday, Mr. Powell said it was “too soon” to say whether he would endorse the Republican nominee for president, and he added that he is reserving judgment for now.

“I’ve been around this town a long time, and I know everybody who is running for office,” Mr. Powell said. “And I make myself available to talk about foreign policy matters and military matters with whoever wishes to chat with me.”

Those words appear to represent an extraordinary shift for a man who made the highest-profile case for the war in Iraq, a war the Democratic Party leadership contends was waged on the basis of politicized intelligence.

Mr. Powell, for his part, has said this interpretation of the pre-war intelligence debate is incorrect. Yesterday, he defended his 2003 presentation of the American case for war, saying he spent five days checking every fact at CIA headquarters before he gave it. The presentation was based on the same intelligence estimate that was made available to Congress, he said, and he noted that many Democrats who served in Congress at the time later said they did not read the classified estimate.

One lawmaker who has not had to make such a statement is Mr. Obama, who in 2002 and 2003 was a state senator in Springfield, Ill., and opposed the war. “Before the war in Iraq started, Obama had the courage to stand up to the politics and propaganda and spoke out against the war, even before the invasion of Iraq,” a spokeswoman for Mr. Obama’s campaign, Jen Psaki, said. “Any time you have the opportunity to seek advice on foreign policy from the former secretary of state, it is a welcome meeting.”

Mr. Obama said in October 2002 that he was “not opposed to all wars,” just “dumb” and “rash” ones. “What I am opposed to is the cynical attempt by Richard Perle and Paul Wolfowitz and other armchair weekend warriors in this administration who shove their own ideological agendas down our throats, irrespective of the costs in lives lost and in hardships borne,” he said at a rally hosted by Act Now to Stop War and End Racism.

Since his election to the Senate in 2004, Mr. Obama has adopted a more moderate stance. While many in his party, including Senator Clinton, have criticized the faulty intelligence leading up to the war, Mr. Obama has co-authored legislation to help secure loose chemical and biological weapons and keep them out of the hands of terrorists.

In October 2005, Mr. Obama accompanied Senator Lugar, a Republican of Indiana who was then chairman of the Senate Foreign Relations Committee, on a fact-finding mission to the former Soviet bloc. In a speech at the Council on Foreign Relations after the trip, Mr. Obama said: “The demand for these weapons has never been greater. … Right now rogue states and despotic regimes are looking to begin or accelerate their own nuclear programs.”

Nonetheless, Mr. Obama has since expressed opposition to the surge of American troops in Iraq and has endorsed plans to withdraw from the country by 2008, a position shared by more than 60% of Americans, according to a New York Times poll in May.

Mr. Powell may not share that position, but he did express pessimism on “Meet the Press” yesterday about the prospects for the surge. He believes that American forces in Iraq are facing a “civil war,” he said, and he noted that the White House has not called the conflict in Iraq a civil war. “The current strategy to deal with it, the military surge, our part of the surge under General Petraeus — the only thing it can do is put a heavier lid on this boiling pot of civil war stew,” he said.

For close Powell watchers, this sort of statement may not be surprising. As secretary of state during the 2004 election season, he hinted to the editorial board of the New York Times that had he known no weapons of mass destruction would be found in Iraq, he would not have supported the war.

More recently, Mr. Powell kept mum after his former chief of staff, Lawrence Wilkerson, said the Bush administration was being run like a “cabal.” In 2005, Mr. Wilkerson helped sink the White House’s nomination of John Bolton as ambassador to the United Nations; Mr. Powell did not sign a letter of former Republican secretaries of state endorsing the Bolton nomination.

Mr. Powell’s positions on a number of national security issues appear to be more in sync with those of Democrats. On “Meet the Press,” for example, Mr. Powell said he would close the military prison at Guantanamo Bay, Cuba, which holds suspected terrorists. “I would simply move them to the United States and put them into our federal legal system,” he said.

A former spokesman for the Republican National Committee, Clifford May, said he thinks it is fine for Mr. Powell to offer his advice to all presidential candidates. “If Colin Powell is advising candidates from both parties on foreign policy, that is commendable,” Mr. May, the president of the bipartisan Foundation for the Defense of Democracies, said. “Foreign policy and national security ought to be beyond partisanship. They have not been in recent years, and that is deeply regrettable.”