And she added: "I think all of America can see that clearly the president is making decisions. He makes many decisions on a whole host of issues every day."
"What we are marking is not 100 days of my presidency; it is 100 days of Congress and the president working together for the American people," he said.
Polls showed favourable job approval ratings ranging from 56-63% but analysts said his standing in the polls could be moved significantly one direction or the other by big events.
Supporters
In what has become a Washington ritual for examining the performance of new presidents, his top advisors defended his record saying he had stuck to his campaign promises.
"I think one thing that the American people have clearly seen over these first 100 days is President Bush does in office exactly what he said he would do," presidential counsellor Karen Hughes said.
And she added: "I think all of America can see that clearly the president is making decisions. He makes many decisions on a whole host of issues every day."
But his opponents painted a different picture, expressing their concerns over the foreign policy front and the environment.
"I don't think it's been that good," Missouri Democrat Richard Gephardt said. "Even by President Bush's own standards he hasn't measured up."
Environmental concerns
Some Democrats gave the president credit for a solid start. "He's done better than expected, but we didn't expect much," said Democratic consultant Dane Strother.
Democrats have seen President Bush as especially vulnerable on the environment, where he has reversed several initiatives by former president Bill Clinton.
His dumping of the Kyoto Treaty on global warming sparked international outrage but has had little impact on his domestic approval ratings.
Some green groups have dubbed Mr Bush the "Toxic Texan" and "worst environmental president ever".
Environmental groups planned to protest across the White House on Monday, exactly at the time of Mr Bush's lunch with lawmakers.
Foreign policy
The Bush administration faced a potentially damaging confrontation with China over the US spy plane incident in which a 24-member crew was detained by the Chinese for 11 days earlier this month.
President Bush emerged largely unscathed and with the support of the majority of the American people for his position.
He has taken a hard line on China and also on North Korea and Russia. His policy shifts have unsettled allies from Asia to Europe.
He will begin consulting with US allies this week on his controversial plans for a missile defence system.
Mr Bush declined to consider his first 100 days a milestone for evaluating his presidency, but relented in the face of massive media coverage.