CLEVELAND, July 1 - President Bush today hailed last week's Supreme Court decision upholding the use of public money for religious school tuition as "just as historic" as the landmark 1954 ruling that school segregation was unconstitutional, and he declared that the United States could not have separate education systems for the rich and the poor.

In his first public comments on the ruling, Mr. Bush plunged into the politically explosive issue of school vouchers that he had so far avoided as president.

Although Mr. Bush had tried to include vouchers in a major education bill he signed early this year, he quickly gave up when he saw that there was not enough support from Congressional leaders for the program.

The president's speech today, in the city that established the voucher program upheld by the Supreme Court on Thursday, signaled that he now felt he had the opening to push aggressively on the issue.

In the 2000 presidential campaign, Mr. Bush supported voucher programs but rarely if ever used the word, a reflection of how divided American voters were on the issue.

"The Supreme Court of the United States gave a great victory to parents and students throughout the nation by upholding the decisions made by local folks here in the city of Cleveland, Ohio," Mr. Bush said to loud applause at the Playhouse Square Center on the eastern edge of downtown.

Advocates of vouchers have praised the 5-to-4 ruling as the most important Supreme Court decision on education since the segregation ruling, Brown v. Board of Education.

Today was the first time, however, that the president said he agreed with them.

"The Supreme Court in 1954 declared that our nation cannot have two education systems," Mr. Bush said. "And that was the right decision. Can't have two systems, one for African-Americans and one for whites.

"Last week, what's notable and important is that the court declared that our nation will not accept one education system for those who can afford to send their children to a school of their choice and for those who can't. And that's just as historic."

Vouchers, Mr. Bush said, are "a constructive approach to improving public education."

"We're interested in aiming toward excellence for every child," he continued. "And the voucher system is a part of the strategy to achieve that here in Cleveland."

Although vouchers are not popular with all Republicans, particularly those who moved to the suburbs for better schools, they are strongly supported by low-income African-Americans whose children attend poor-quality city schools. Mr. Bush received little support in the last presidential election from black voters and his political advisers are eager to increase his support among African-Americans in any way they can.

Today before an audience of nearly 3,000 people, Mr. Bush singled out a black Cleveland resident who is an advocate for vouchers, Roberta Kitchen.

"Where's Roberta?" Mr. Bush asked from the stage, then found her and waved.

"Hi, Roberta," he said. "Roberta is a mom of five children, and her passion is a passion which is shared by moms all across America. Her passion is pretty simple: I want my children to go to a safe school where he or she can realize their full potential."

Conservatives predicted after the Supreme Court decision last week that Mr. Bush would be forced to embrace vouchers more publicly. Democrats not unhappily agreed, and asserted that Mr. Bush would become more identified with the right - notwithstanding vouchers' appeal to urban blacks - and less of the centrist leader he has tried to become in education.

Mr. Bush's embrace of vouchers today was quickly criticized by Senator Edward M. Kennedy, Democrat of Massachusetts, a leading sponsor of the education bill. The senator allied himself with Mr. Bush for the passage of the bill, but rebuffed him in his efforts to add vouchers. Mr. Kennedy has also been increasingly at odds with the president over what he considers the administration's failure to provide enough money to finance the bill's goals.

"Private school vouchers may pass constitutional muster, but they fail the test when it comes to improving our nation's public schools," Mr. Kennedy said in a statement. "It's flat wrong to take scarce taxpayer dollars away from public schools and divert them to private schools."

Under Cleveland's six-year-old program, about 3,700 of the district's 75,000 children use vouchers worth up to $2,250 to help pay for private school tuition. Nearly all of these students attend religious schools. Today, Education Secretary Rod Paige called the city "ground zero for freedom of choice in public schools" as he introduced Mr. Bush.

The president, in an unusually long 38-minute address to people from school choice organizations and charities, spent much of his time promoting his education legislation, the No Child Left Behind law, which mandates annual testing of children in Grades 3 to 8 and offers tutoring for students in failing schools.

"It's easy to walk into a classroom full of inner-city African-Americans, for example, and say, `You can't learn, we'll move you through,' " Mr. Bush said. "Or how about classrooms full of children whose parents don't speak English as a first language - it's easy to quit on those kids. Heck, it's hard to educate a child whose parents don't speak English; why don't we just shuffle them through the system?

"That means you have low hopes, low standards, low expectations. We start with a different premise: every child can learn, regardless of their circumstances."

Mr. Bush also used his two hours and 45 minutes in a politically crucial state that he won comfortably in 2000 to remind voters of his "compassionate conservative" agenda. Today he promoted his changes to the welfare laws, his plan to give federal money to religious charities and his program to increase home ownership among minorities.

He also, as he almost does, spoke of the campaign against terrorism, but he said that he was not only interested in war.

"Oh, I know that in the midst of this war there is a lot of warlike talk, and I'm as guilty as - I'm guilty," Mr. Bush said, to laughter. "I talk that way. But I want you to know, I love peace."