Residents of the Florida Keys were ordered to evacuate yesterday as Tropical Storm Rita approached hurricane strength on a path similar to that of Katrina, which devastated the Gulf Coast three weeks ago, and the mayor of New Orleans suspended a plan to start repopulating his flood-ravaged city.

With Rita forecast to become a Category 1 hurricane last evening and to reach Category 2 strength today, tourists streamed out of the Keys and residents boarded up homes and shops.

But a potentially greater threat looms later in the week, when Rita is projected to intensify over the warm waters of the Gulf of Mexico, just as Katrina did late last month before slamming ashore about 60 miles southeast of New Orleans. On its current path, meteorologists said, Rita could hit the Texas coast by the weekend, bringing hurricane-force winds and torrential rains to an area that houses thousands of evacuees from flooded New Orleans.

In view of the new storm, New Orleans Mayor C. Ray Nagin announced he was calling off his plan to allow displaced residents to return, one neighborhood at a time. (See story, A1.)

Rita is "not an exact reprise" of Katrina, "but it's probably pretty close," said Frank Lepore, a spokesman for the National Hurricane Center in Miami. "It's got similar characteristics, except it's just a little lower in latitude. The issue is what happens when it gets out over the very warm waters of the central Gulf."

The storm was packing winds of 70 mph last night and was projected to hit Key West about 6 p.m. today with winds around 105 mph, making it a Category 2 hurricane, Lepore said.

As Rita gathered strength, the hurricane center issued a hurricane warning for the southern tip of the Florida peninsula and for all of the Keys. It said that at 11 p.m. Eastern time, Rita was 270 miles east-southeast of Key West and was moving west-northwest at 14 mph.

The hurricane center said the Keys could be hit with storm-surge flooding of six to nine feet above normal tide levels, "along with large and dangerous battering waves."

A mandatory evacuation order issued by Monroe County, Fla., covered about 80,000 people in the Keys, including 25,000 residents of Key West. Buses were sent to Key West High School to evacuate people who needed help to leave, and a military C-130 transport plane was dispatched to Key West Hospital to evacuate patients. In addition, about 134,000 Miami-Dade County residents who live in coastal areas were under a voluntary evacuation order.

A voluntary evacuation was set to start today in Galveston, Tex., where officials said residents who could not leave on their own could take buses -- and their caged pets -- to shelters starting tomorrow.

President Bush, after a meeting with homeland security officials to discuss Hurricane Katrina relief efforts, suggested that in view of Rita's approach, it would be a mistake for evacuees to return to New Orleans.

Rita "now looks like it's going to head out into the Gulf, and could track Katrina, or it could head further to the west," Bush told reporters. "But, nevertheless, there is deep concern about this storm causing more flooding in New Orleans."

Nagin "has got this dream about having a city up and running, and we share that dream," Bush said. "But we also want to be realistic about some of the hurdles and obstacles that we all confront in repopulating New Orleans."

He said that if Rita brings heavy rains, "there is concern from the Army Corps of Engineers that the levees might break. And so, therefore, we're cautious about encouraging people to return at this moment of history."

According to Lepore, a five-day projection shows Rita reaching Category 3 strength in the middle of the Gulf, with sustained winds of about 115 mph and gusts up to 130 mph. Although its path is difficult to predict at this point, the latest projection has Rita heading toward Houston, a major oil industry center that is also home to thousands of Katrina evacuees.

One concern is that Rita will hit "the general area where all these folks from New Orleans have been evacuated," Lepore said. "And there is enough hardship in that area as it is without throwing another hurricane at them."

John Silvis removes a television from his trailer home as he prepares to leave Florida City because of Tropical Storm Rita. It is projected to hit the Florida Keys as a hurricane and then strengthen over the Gulf of Mexico.