By Bruce Drake, CQ Staff

Illinois Sen. Barack Obama , who came off a string of presidential primary and caucus victories in February that raised questions about the viability of New York Sen. Hillary Clinton’s rival campaign, is weathering a brutal March in which his once-growing leads in national and state polls have stalled or vanished.

Many polls indicate that Obama has suffered from the one-two punch of attacks leveled by Clinton that Obama lacks experience (such as the now-famous 3 a.m. crisis call ad used by the Clinton campaign) and the highly publicized fallout over past racially divisive remarks made by Rev. Jeremiah Wright, the former pastor of the Chicago church attended by Obama and his family.

Obama’s slippage does not mean that the path to the nomination has grown easier for Clinton. Obama still leads her in the Associated Press delegate count by 1596 to 1434, with just over 1,000 delegates yet to be claimed.

Clinton’s efforts to close the delegate gap continue to be hindered by the Democratic National Committee’s disqualification of the January primaries held in Michigan and Florida — both of which Clinton won — because those contests violated the national party’s scheduling rules for nominating contests. Efforts to implement proposals to stage June re-votes of those primaries have been stymied in Michigan and in Florida.

There are only a few polls so far conducted after the speech Obama delivered Tuesday in Philadelphia on bridging the nation’s racial divisions, in which he tried to defuse the controversy over Wright’s comments. (Video) (Transcript)

The numbers suggest that Obama’s Philadelphia speech may have helped him reverse some of the damage, although there is still a significant number of voters left with doubts.

A Fox News/Opinion Research poll published Thursday said most Americans — 72 percent — say they have heard about Wright’s controversial oratory, but more than half said they do not believe Obama shares his views.

Fifty-four percent of voters said Obama’s association with Wright did not make them have doubts about him, but that left 35 percent of voters who did have such doubts after Wright’s comments became known.

Gallup’s daily national tracking poll, which had Clinton moving as much as 7 percentage points ahead of Obama earlier in the week, on Friday had her lead at a statistically insignificant 47 percent to 45 percent. Gallup said “the surge in Democrats’ preference for Clinton that Gallup detected earlier in the week has started to move out of the three-day rolling average, and the race is back to a near tie. It is possible that Obama’s aggressive efforts to defuse the Wright story, including a major speech on the race on March 11, have been effective.”

Still, Gallup cautioned, “Obama has yet to recover fully from the apparent damage done by the Wright controversy. It was only one week ago that Obama led the race by a significant six-point margin over Clinton, 50% to 44%.”

A Rasmussen Reports survey conducted March 19-20, said that among the 84 percent of likely voters who had seen or heard at least some portion of Obama’s speech, 51 percent rated it good, 26 percent said it was fair and 21 percent said it was poor. The partisan breakdown had 67 percent of Democrats saying it was good compared to 53 percent of unaffiliated voters and 31 percent of Republicans. Along the racial divide, 86 percent of black voters called it good compared to 45 percent of white voters.

Rasmussen said 56 percent of voters said they remained somewhat or very concerned about Obama’s relationship with Wright despite the speech.

An earlier Reuters-Zogby poll said that the 14-point lead Obama enjoyed in February in its survey had dwindled to a statistically insignificant 47 percent to 44 percent edge. Zogby attributed Obama’s slide to the questions raised by Clinton and others about his experience and the controversy over Wright. Both polls were conducted before Obama’s speech.

CBS News re-interviewed voters it had canvassed prior to Obama’s Philadelphia speech during the controversy over the rhetoric of Wright. That poll had said sixty-five percent said Wright’s oratory made no difference in how they viewed Obama and 30 percent said the story made them look less favorably on Obama. Its new poll said that 69 percent of voters who have been following this story said Obama did a good job in his Philadelphia speech on race relations while 20 percent thought he did a poor job.

Seventy percent of voters in the CBS poll said the controversy over Wright would make no difference in how they vote. But Obama did suffer a decline in the number of voters who believed he would unite the country - from 67 percent in February to 52 percent now.

Even as the national numbers tighten, Clinton has widened her lead in the next big primary state, Pennsylvania, which holds an April 22 contest that will apportion most of the state’s 188 delegates. A Franklin & Marshall poll released Thursday had Clinton ahead 51 percent to 35 percent, with Obama’s favorability rating dropping 10 points since F & M’s last poll.

“Considering the losses that Obama took in Texas and Ohio, and when you add to it the negativity of the comments attributed to Reverend Wright, that’s two shots to the body that Obama is having trouble dealing with,” said Pennsylvania political scientist Joseph DiSarro.

Public Policy Polling, a Democratic firm, said that the Wright story had hurt Obama in North Carolina, which holds a May 6 primary and will send 134 delegates to the Democratic National Convention in Denver this August. Obama’s lead there had slipped to 44 percent to 43 percent in PPP’s poll, a drop of 4 points, although its survey was conducted before Obama’s speech on race issues.

One dynamic that has yet to play out decisively is whether the strengths that attract voters to Obama trump his weaknesses.

One such “matchup” might be the impact of Obama’s personal appeal versus the doubts about his experience. The Fox News poll asked voters about the recent controversial statement by 1984 Democratic vice presidential nominee (and Clinton supporter) Geraldine Ferraro that “if Obama was a white man, he would not be in this position.” Only 14 percent agreed with that.

But what was equally interesting is that given these choices of reasons he has gotten so far in the presidential race — Qualified Candidate, African-American, Inspirational Speaker, Combination Of These, Other and Don’t Know — 38 percent of all respondents answered “inspirational speaker,” compared to 22 percent who said “qualified candidate.” The margin was much smaller among Democrats who responded to the polls, with 32 percent citing Obama’s speaking skills to 29 percent who picked the “qualified candidate” choice. Self-described independents chose “inspirational” over “qualified” by 41 percent to 19 percent.

For former first lady Clinton, poll participants were given the choices of “qualified,” “woman” and “wife of a former president.” Among all respondents, “wife of a former president” was chosen by 37 percent to 28 percent for “qualified.” Democratic respondents alone reversed that with 39 percent saying “qualified” and 30 percent saying “wife of a former president.

On the experience question, a CNN/Opinion Research poll conducted last week reported about 60 percent of Americans said Obama did not have the right experience to be president, compared to 38 percent for Clinton and 31 percent for McCain.

A USA Today/Gallup poll conducted during the same period — which the Obama campaign touted Friday because it reported that Clinton had an “Honesty Gap” compared to McCain and Obama — ranked Obama highest against Clinton and McCain in the categories of “cares about people like you,” “shares your values,” “understands the problems Americans face in their daily lives,” “would work well with both parties in Washington to get things done,” and “is someone you would be proud to have as president.”

Obama rated lowest in the categories of “strong and decisive leader,” “has a clear plan for solving the country’s future problems, and “can manage the government effectively.”