President Bush today nominated a Republican congressman, Rep. Porter J. Goss of Florida, to head the Central Intelligence Agency, describing him as a "reformer" who "knows the agency and knows what's needed to strengthen it."

Goss, a former officer in the CIA's clandestine service, has long been mentioned as a leading candidate to replace George J. Tenet, who resigned as CIA director in July.

But there had been some delay in naming Tenet's replacement, in part because of the potential for opposition in Congress in the middle of the presidential campaign. The appointment of Goss is subject to confirmation by the Senate.

Reactions to the nomination were mixed. Some Democrats expressed support, but others came out in strong opposition, calling the choice a partisan political move.

Sen. John F. Kerry (D-Mass.), the Democratic candidate running against Bush in the November election, called for "fair, bipartisan and expeditious confirmation hearings" on Goss's nomination. But he said it was more important to move quickly on creating a new position of national intelligence director as recommended by the commission that investigated the Sept. 11, 2001, terrorist attacks.

"The most important thing we can do right now is reform and strengthen our intelligence services as the 9/11 commission has recommended," Kerry said in a statement. He said he hopes Goss "shares this view and will now support the creation of this important post."

Sen. Charles E. Schumer (D-N.Y.) also said the key issue is whether Goss endorses the Sept. 11 panel's recommendations. He called Goss "a fine man" and said the fact that the nominee is a Republican congressman does not bother him.

But retired Adm. Stansfield Turner, who headed the CIA in the Carter administration, said, "This is the worst appointment that's ever been made to the office of director of central intelligence because that's an office that needs to be kept above partisan politics." Turner, who supports Kerry's presidential candidacy, said Goss was chosen "to help George Bush win votes in Florida" in November, the Associated Press reported.

Sen. Jon S. Corzine (D-N.J.) said he was "disappointed" by the choice, arguing that "this position should be filled by a nonpartisan individual of unquestioned independence."

Sen. Orrin Hatch (R-Utah), expressing the prevailing GOP sentiment, said Goss is "uniquely qualified" not only to lead the CIA, but to represent the agency in congressional hearings and steer it through a period of reform.

A fellow Republican, Sen. Mike DeWine of Ohio, said Goss has the qualifications to be the nation's new national intelligence director, if the Sept. 11 commission's recommendation for such a position is adopted by Congress. Goss is someone who could look the president in the eye "and tell him what the truth is and not flinch," DeWine said.

Administration officials said the announcement was intended to send a signal of stability at a time when the intelligence services are roiled by competing reorganization plans. Officials said they were especially concerned about the morale of the CIA's employees.

Bush took pains during a Rose Garden announcement this morning to praise the agency's work, while at the same time acknowledging the need for change. Bush called Goss "the right man to lead this important agency at this critical moment in our nation's history."

He said he looked forward to Goss's judgments "as to how best to implement broader intelligence reforms," including the recommendations of the Sept. 11 commission, which have been partially embraced by the president and are currently the subject of congressional hearings.

While some in Congress have pushed for adoption of all of the Sept. 11 commission's 41 recommendations, Goss has been among those urging caution, saying a rush to reform the intelligence community could lead to the wrong changes.

"The unintended consequences of action we take could wreak havoc if we get it wrong," Goss said during one hearing to consider reforms. "So we aren't going to go there."

"What many American's don't realize," Goss said in a brief statement as he stood with Bush today, "is that we've got an awful lot of people around the globe doing very, very hard work with long hours and in dangerous conditions. The essence of our intelligence capability is people, and we have some wonderful Americans who are doing a great job."

Goss has been in Congress since 1989. He is a former Army intelligence and CIA officer and chairman of the House Permanent Select Committee on Intelligence.

Goss, 65, who served as a CIA case officer for nine years beginning in 1962, had previously announced he would retire from Congress at the end of the year.

Although administration officials have privately predicted that winning Senate confirmation for Goss would be little more than a formality, some Democrats have disagreed, predicting that such hearings would assertively probe both the CIA's performance under Bush and Goss's fitness for the job.

Democrats have urged Senate Minority Leader Thomas A. Daschle (D-S.D.) to prepare for an extensive confirmation hearing this fall, according to several Democratic congressional aides.

White House officials had said earlier they were contemplating leaving Tenet's top deputy, John E. McLaughlin, as the acting head of the agency.

But McLaughlin was intimately involved in many of the decisions and conclusions that have been called into question in several investigations of the agency's performance before and after Sept. 11, 2001. Bush aides have also said the president wanted someone who can play a strong leadership role within the agency and in public.

Administration officials said Bush focused on Goss as his choice for the job for the past few months.

Bush advisers have said that naming a replacement for Tenet would show that the president was taking seriously the need for changes in the intelligence community. But several Democrats have noted that if Kerry won the November election, it would be unlikely that he would keep Goss, should he win Senate approval.

Administration officials have said that if Bush were to choose someone inside the administration, it would risk a drawn-out inquest into the decision-making that led to the invasion of Iraq, which is the subject of several investigations.

But Democrats on the Hill have disputed the idea that Goss would sail through the process. "We could have a referendum on the CIA," one senior Democratic staff member has said.

Intelligence will come under close scrutiny during the presidential campaign, one reason that led Tenet to leave before the end of the year. While Republicans said choosing Goss would give Bush a clean break and allow him to say that changes were being made, Democrats have in the past suggested that some would describe Goss as an attempt to politicize the agency directorship.

Sen. John D. Rockefeller IV (D-W.Va.), ranking member of the Senate Intelligence Committee, has told aides he is concerned that Goss, a vocal supporter of Bush's, has become "too political" for the CIA director job, an aide to the senator said last month.

Goss was selected by the campaign of Bush and Vice President Cheney to critique a June 2 national security speech by Democratic presidential candidate Kerry. Goss called Kerry's nonproliferation proposals "unrealistic and dangerously naive," asserting that they amounted to saying, "We're going to get all the nukes in a lockbox somehow."

When the intelligence authorization bill was on the House floor last month, Goss gave what could be considered a speech in support of his candidacy for CIA director.

"For the past seven-plus years, I have been working to refit the intelligence community for its future . . . to posture it for the days ahead. We have always worked hard on the committee to create a constituency for intelligence inside and outside of this institution. We have insisted that the committee be both supportive advocates and constructive overseers."

The report on the bill by Goss's panel sharply criticized the CIA for "ignoring its core missional activities" and having "a dysfunctional denial of any need for corrective action."

In an unusually frank letter, Tenet wrote Goss that his criticism was "ill informed" and "frankly absurd."

Goss is the son of a metals company sales manager. He grew up in Waterbury, Conn., and attended Hotchkiss prep school and Yale University, majoring in ancient Greek. (Goss also speaks Spanish and French.)

At Yale, he joined the Army ROTC and made his first contacts with the CIA.

He trained as a military intelligence officer after graduation, and by 1962, he was working at the CIA, deployed to Miami in time for the Cuban missile crisis.

Goss has declined in past interviews to detail his activities. In a 2002 interview, he told The Washington Post that "I had some very interesting moments in the Florida Straits."

The CIA also sent Goss to Haiti, the Dominican Republic, Mexico and Western Europe.

In 1970, Goss was hospitalized in Washington for a massive staph infection of his heart and other organs. The illness put him in a wheelchair. He retired from the CIA and moved to Sanibel Island off Florida's Gulf Coast.

There, he started a weekly newspaper and became politically active. In December, 1974, he was elected the island's first mayor -- a dollar-a-year job. Sen. Bob Graham (D-Fla.), then the governor of Florida, appointed Goss to fill a vacancy on the Lee County Commission.

In 1988, Goss ran for Congress and won.

Washington Post Staff Writer Richard Leiby contributed to this story.