GALVESTON, Texas (CNN) -- President Bush heads to hurricane-ravaged south Texas on Tuesday with a message that the federal government will be there with aid and support.

"My message will be that we hear you, and we'll work as hard and fast as we can to help you get your lives back up to normal," Bush said Monday.

With Bush on the way to Texas, city leaders in Galveston were urging those who rode out the storm on the barrier island to leave immediately.

There's not enough clean drinking water to serve the needs of the 15,000 to 20,000 people who stayed on the island, City Manager Steve LeBlanc said Monday, and there would be a "downward spiral if everybody started coming back."

The city's resources are "stretched to the max," and it could be a month before electricity is restored. The cleanup will be massive, he said, and the city is "unsafe."

"Sometimes the aftermath of the storm is worse than the storm itself," Galveston Mayor Lyda Ann Thomas said. "There's nothing to come here for right now. ... Please leave."

But those who stayed were trying to make the best of their muggy, tree-strewn, powerless city.

Amy Reid and her neighbors found a good use for all the frozen dinners that had piled up in their freezers, pooling them as some kind of high-sodium feast they might have to subsist on for a long time.

As of Monday night, there was only one convenience store open in Galveston and one was lucky to find beef jerky and fruit roll-ups on the shelves.

Reid and her new friends cooked on a grill and slept on her porch, choosing to suffer the bugs rather than spend a restless night in a sauna-hot house. Her home, hoisted on stilts, was not flooded.

"We've got a whole group of people along the block," she said. "One guy down here has a generator so he charges our phones up and our laptops up." DVDs on a laptop pass the long wait before Galveston is up and running again.

North of Galveston, Texas Gov. Rick Perry urged residents who evacuated Houston, the nation's fourth-largest city, not to hurry back to their homes.

But Sarah Allen returned to her Houston home Monday, finding it in relatively good shape. Her carpeting was wet from leaks near a sliding glass door, but her apartment had not flooded. She, her boyfriend and six other people rode out Hurricane Ike at a friend's house.

"Lots of trees are down in people's apartments," she said. "The covered parking lot has a metal roof, and some of it has fallen on cars. Some was rolled up."

About 150,000 of the 220,000 residents who evacuated ahead of the storm were still out of their homes Monday, said Judge Ed Emmett, chief executive of Harris County, which includes Houston.

City officials did not lift a boil-water order as expected Monday afternoon, saying water in one location was being retested.

Power has been restored to at least 500,000 customers in the Houston area, according to the Harris County Office of Homeland Security and Emergency Management, but another 1.5 million people in the state still have no electricity.

Marilyn Davidson's Clear Lake neighborhood in Houston was strewn with downed trees. She and her husband relied on a battery-powered radio for information and loaded their refrigerator with ice before the storm.

"Everything in there stayed pretty cool," she said. "We had milk out of it this morning." The wait outside her regular grocery store was a half-hour so the couple went to a pharmacy and stocked up on items they said they probably would never eat such as canned mixed nuts and chicken broth.

Davidson did have the one most desired and scarce of goods -- gasoline.

At least 14 Texas refineries closed in the hours before the hurricane hit, taking away more than 20 percent of the nation's oil capacity, The Associated Press reported. Across the nation, gas prices soared for the third straight day, jumping a full dollar at some stations.

Thousands of people remained in shelters, wondering what their homes would be like when they returned. Others waited in line to get water, ice and food at 60 distribution sites the Federal Emergency Management Agency had established across Texas.

Perhaps the most dire area of the state was Bolivar Peninsula, a resort on Galveston Bay where entire neighborhoods were destroyed. A rescue team on Monday saved 60 people who were stranded there among homes leveled to their foundations. On Sunday, a Galveston County sheriff's official said three bodies were pulled from storm wreckage in Port Bolivar.

Ike and its remnants left at least 27 people dead from the U.S. Gulf Coast to the Great Lakes. The remnants moved into Canada early Monday.

Hurricane-force winds from the storm were felt as far north as Kentucky, and heavy rains flooded streets in Chicago, Illinois. See Chicago's swamped streets

By Tuesday morning, authorities were warning of possible flooding along the Missouri and Mississippi Rivers as weekend rains drained off the land.

More than 2 million people in Ohio, Kentucky and Indiana were without power on Monday as hurricane-force winds raked the region, the AP reported.

Hundreds of school districts across Ohio were closed, and people crowded coffee shops and restaurants with power and Internet access on Monday as they waited for their homes to get power back, the AP reported.

In suburban Cincinnati, Ohio, long lines were reported at the few gas stations that had power.

Deaths related to the storm were reported in Louisiana, Arkansas, Indiana, Missouri and Ohio as well as Texas.

Louisiana Chief Medical Officer Louis Cataldie confirmed four deaths as a result of the hurricane -- two in Terrebonne Parish and two in Jefferson Davis Parish.

Trees toppled by Ike killed eight people -- four in Indiana, three in Ohio and one in Arkansas.

Two people drowned in Indiana and another in Missouri.

Two others died in the St. Louis, Missouri, area, but the cause of their deaths was unclear, said Missouri State Emergency Operations Center spokeswoman Susie Stonner.