President Barack Obama’s decision to withhold photographs of abused detainees marks the next phase in the education of the new president on the complicated, combustible issue of torture.

Conservatives praised the move as a sign of Obama’s growth in office, while civil libertarians denounced it as a betrayal of the change he’d campaigned on.

But it also marked a growing recognition inside the White House of how explosive the question of torture has become — swamping his predecessor’s legacy, entangling the speaker of the House and threatening to overwhelm Obama’s agenda.

“He plainly does not want his agenda sidetracked by a long debate over torture — much less high-profile prosecutions,” said former Clinton aide Paul Begala. “And yet there is no avoiding the issue. It will not go away, and wishing it away won’t work.”

Begala said he favors establishing an independent commission to investigate torture, which Obama and Secretary of State Hillary Clinton both appeared to support for one day last month before backtracking.

The administration also has sent mixed signals on prosecuting former Bush administration officials involved in devising interrogation policy.

And Obama has departed from campaign rhetoric on other national security matters in a series of quiet legal filings, from asserting the state secrets privilege to trying to block court access for detainees in Afghanistan.

House Speaker Nancy Pelosi, meanwhile, has found herself under intense scrutiny over what she knew about Bush administration interrogation policy and when — and what she did to oppose it.

The uproar seems to have vindicated — politically speaking — the voices inside the administration who opposed releasing the initial Bush “torture memos” four weeks ago.

Some Obama advisers have argued — as White House chief of staff Rahm Emanuel did last month — that “it’s not a time to use our energy and our time in looking back” or for “any sense of anger and retribution.”

Even Obama initially took that stance — but appeared to abandon it abruptly, and rather clumsily, in releasing the memos, then raising the possibility of a 9/11 Commission-style inquiry into the practices.

In retrospect, avoiding inquiries into the past may always have been impossible for Obama, who made a full-on criticism of George W. Bush’s war on terror a central part of his campaign. And it certainly became more unlikely when former Vice President Dick Cheney mounted a public campaign to defend the practices he had championed.

But the White House now finds itself treading with extreme caution on uncertain and dangerous ground — as reflected in Obama’s sudden reversal on releasing the photos.

“This team got in and had no idea what they were going to find,” said the executive director of the National Security Network, Heather Hurlburt, a former Clinton administration official. “There are so many messy, loose ends in this that we don’t even know about yet.”

Though the decision to release the torture memos was made after an intense internal debate, the decision about the photos appeared to have come with less reflection.

Obama had not even seen the detainee photos before deciding to reveal them — a move that came when the White House agreed to release the pictures by May 28 in response to court orders, and not to seek review by the Supreme Court.

Since then, Obama has personally examined the photos, saying they are less “sensational” than photographs from the Abu Ghraib prison in Iraq. But he still decided to reverse course and try to block their release.

“I am concerned about how the release of these photos would impact on the safety of our troops,” Obama said Wednesday in a short statement outside the White House.

Obama insisted — in a brief exchange with POLITICO — that the Republican outcry from his release of the “torture memos” had nothing to do with his reversal on the photos.

Asked as he walked from his televised news conference whether the controversy over the torture memos had influenced his decision to fight to withhold the photographs, Obama turned, looked stern and said “No.”

But his move carries political implications. Liberal anti-torture advocates reacted angrily to Obama’s decision Wednesday — accusing him of caving in on a central promise from the campaign to expose and ban the most aggressive Bush-era terror practices.

ACLU attorney Jameel Jaffer even accused Obama of adopting arguments put forward by his predecessor.

“The most disturbing thing that happened today was the president endorsing the Bush administration’s narrative that this was the fault of rogue soldiers and that the abuse was isolated,” Jaffer said. “In fact, it was systematic and created by the policies that were put in place.”

Despite Obama’s problems on the left, recent polls suggest that the president has closed the traditional “security gap” between Democrats and Republicans, with one Washington Post survey even finding that Americans trust him more on national security than on other issues.

He has projected calm on the international stage, won bipartisan support in Afghanistan and Iraq, and won credit even from Republicans for approving the mission to kill three Somali pirates to rescue a U.S. ship captain held hostage.

“When you go from being a senator to being commander in chief, you’re going to be on a learning curve,” Rep. Mark Kirk (R-Ill.) told POLITICO. “Over time, you become more conservative as you deal with the true enemies of the United States.”

Obama has become “more realistic about the threats we face,” said Sen. Lindsey Graham (R-S.C.).

But Republicans have also begun to sharpen their political attacks on the complex, slow-moving issues around detainee policy. The plan to move detainees from Guantanamo Bay to domestic jails prompted Republicans to introduce the Keep Terrorists Out of America Act, though Obama has signaled that he’ll renew the Bush administration’s military commissions for trying those detainees, tightening commission rules rather than abolishing them outright.

“They have been extremely careful to see that they don’t lurch in regards to national security — prudence is everything,” said Matt Bennett, a vice president at Third Way, a progressive think-tank group.

“There’s a debate here in which the former vice president has accused this president of undermining American security,” said Jeremy Rosner, a Democratic pollster who said he’d just completed a large survey on national security attitudes, due out next week. “It’s a pretty serious charge, but I think that is not how the public sees this new administration right now.”

Correction: In an earlier version, a quote was misattributed to Jeremy Rosner, but was corrected to say Matt Bennett, a vice president at Third Way.