WASHINGTON — Over the past few weeks, some of Barack Obama's most fervent supporters have come to an unhappy realization: The candidate who they thought was squarely on their side in policy fights is now a president who needs cajoling and persuading.

Advocates for stem-cell research thought Obama would quickly sign an order to reverse former President George W. Bush's restrictions on the science. Now, they are fretting over Obama's statement that he wants to act in tandem with Congress, possibly causing a delay.

Critics of Bush's faith-based initiative thought Obama had promised to end religious discrimination among social service groups taking federal money. But Obama, in announcing his own faith-based program this month, said only that the discrimination issue might be reviewed.

And Obama's recent moves regarding the trials of detainees have left some liberal groups and Bush critics, including the American Civil Liberties Union, feeling betrayed, given that Obama was a harsh critic of Bush's detainee policies when running for office last year.

The anxiety is also being felt in the labor movement, one of Obama's most important support bases. Some union officials and their allies are frustrated that at a critical point in negotiations over his stimulus package, Obama seemed to call for limits on "Buy American" provisions in the bill aimed at making sure stimulus money would be spent on U.S.-made materials.

Obama has been president for less than a month, and his liberal critics concede that the economic crisis understandably has taken the focus off their issues. But some of the issues in play were crucial to building excitement on the left and mobilizing grass-roots support for Obama's candidacy.

"He made very clear promises, and he should live up to them," said Arthur Stamoulis, director of the Oregon Fair Trade Campaign, which received an unqualified "yes" from Obama on a campaign questionnaire last year when the group asked if he would support "Buy American" requirements. "The fact that he's hedging on this is not promising. He's catering much too much to the desires of Republicans who are not going to support the change that voters wanted."

Thea Lee, policy director of the AFL-CIO, said: "We would like to have him stand more forthrightly behind the positions that he took during the campaign."

Obama has long said his administration will be driven by competence and not ideology. He has blamed the nation's problems on a failed and highly partisan political system, and he has said solutions should come by building coalitions that cross the traditional battle lines in Washington policy fights.

Moreover, say White House aides, Obama already has fulfilled promises such as enacting a labor-backed pay equity law and beginning the process of closing the detainee prison at Guantánamo Bay, Cuba, "Given that we have only been here for three weeks, that is a pretty good start," White House spokeswoman Jennifer Psaki said.

Yet, for some who supported him, Obama's recent actions contain either outright abandonment of what they thought had been campaign promises or at least a hesitation on Obama's part to follow through quickly and clearly.

Union leaders were taken aback earlier this month when Obama, during television appearances discussing the stimulus legislation, spoke skeptically of "Buy American" provisions in the bill giving U.S. makers of steel and other materials an advantage in bidding for contracts.

"Buy American" rules remain in the stimulus bill that the president is scheduled to sign today, but labor advocates were alarmed by Obama's willingness to insert himself in the debate as a champion of business concerns. They said his stance was far different than during the presidential election, when Obama was trying to win union votes and called for rebuilding America with union-made materials.

Obama's new language was a "disturbing" sign, said Jeff Faux, an economist at the union-backed Economic Policy Institute. He said the president had "moved so quickly to concede on this question without really drawing the debate out."

Now, some labor advocates worry about how aggressively the new president will push to fulfill other key campaign promises, such as passage of the so-called "card check" legislation that would make it easier to form labor unions.

At the ACLU, executive director Anthony Romero said his group's disappointment is "deep and unparalleled" after the Justice Department decided to keep in place one of the most controversial legal tactics of the Bush anti-terror arsenal: using the "state-secrets" doctrine to block lawsuits by detainees.

The Justice Department employed the state-secrets doctrine last week in arguing that a case should not proceed because it might lead to the disclosure of classified information. As a candidate, Obama had attacked Bush for using the tactic and had pledged to reverse such policies.

"Clearly, the state-secrets campaign promise is broken," Romero said.

Advocates of medical research using human embryonic stem cells are also watching Obama. As a candidate, Obama told the Web site sciencedebate2008.org that he would reverse Bush's restrictions on federal funding for the research "through executive order." Immediately following his election victory, transition director John Podesta told reporters the stem-cell order would be one of the first priorities.

But Obama recently signaled in remarks to Democratic lawmakers that he intended to wait for action in Congress.

Wary of a delay, one prominent advocacy group sent Obama a letter recently saying he had pledged to revoke the Bush order. "We wanted him to know that we were still counting on the campaign commitment," said Amy Comstock Rick, president of the Coalition for the Advancement of Medical Research.

Senior Obama adviser David Axelrod told Fox News on Sunday that action could come soon.

Under Bush's faith-based initiative, religious groups taking federal money to provide social services were allowed to discriminate in hiring against people of other religions.

Obama, as a candidate, had seemed to attack that policy when he said groups receiving federal grants should not discriminate against the people they serve, "or against the people you hire on the basis of their religion."

But instead of reversing Bush's policy, Obama has said his own faith-based team might conduct a case-by-case review.

"People know that this looks like a promise that has been deep-sixed," said Barry Lynn, president of Americans United for Separation of Church and State.

While Lynn said he was upset by Obama's Feb. 5 announcement of his policy on religious discrimination, "I'm more disillusioned now, because there has been weeks of healthy criticism and yet no movement by the White House."