Blog Posts by Olivier Knox, Yahoo! News

Click image to see more photos. (ABC News)

First Lady Michelle Obama on Tuesday put the Supreme Court at the core of President Barack Obama's argument for reelection, telling supporters that the vote in November could affect Americans' security, freedoms and whether they can "love whomever we choose" -- a reference to the fight over gay and lesbian rights.

"This President has brought us out of the dark and into the light," she said in a speech at a rally in Nashville. "I hope you all are fired up and ready to go."

Her comments came as Washington awaited a ruling from the nine justices on whether her husband's landmark health care law is constitutional. A decision could come in June.

"We cannot forget the impact the Court's decisions will have on our lives for decades to come — on our privacy and security, on whether we can speak freely, worship openly, and love whomever we choose," she said in a ringing defense of the president's record.

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President Barack Obama still has confidence in Secret Service Director Mark Sullivan despite a widening scandal over agents allegedly cavorting with prostitutes on the margins of an international summit in Cartagena, Colombia, the White House said Tuesday.

"Director Sullivan acted quickly in response to this incident and is overseeing an investigation, as we speak, into the matter," spokesman Jay Carney told reporters at his daily briefing.

The agency announced Monday that it had stripped 11 agents tied to the scandal of their "top secret" clearance and seized their official identification and firearms.

The president made clear "he believes that all of us who travel abroad represent our country and the people of the United States and we need to behave with the utmost, the highest level of integrity and probity," Carney said.

"If in fact it turns out that some of the reported allegations are true he will be angry about that," Carney said, echoing Obama's own comments in Colombia.

Fighting to contain voter anger over sky-high gas prices, President Barack Obama urged Congress to toughen penalties for improper manipulation of oil markets and called for stricter government oversight of energy markets.

"None of these steps by themselves will bring gas prices down overnight," the president said in the White House Rose Garden. "But it will prevent market manipulation and make sure we're looking out for American consumers."

The American Automobile Association puts the national average price for a gallon of regular at $3.904.

On a White House-organized conference call to preview the announcement, senior administration officials refused to say how much improper or illegal manipulation added to the per-gallon price at the pump or when, if at all, Americans could start seeing the policy reduce the cost of filling up.

"You won't find the administration making projections about the particular impact, or the particular price impact, of any particular policy," one official told reporters on condition of anonymity. "We would leave that to outside analysts to disentangle."

And Republicans scoffed and pointed to the Obama administration's Oil and Gas Price Fraud Working Group, which was announced with great fanfare in April 2011. The task force "has met only four or five times since its creation" and "has never reported to the public," according to one published news account.

"Listen, the president has all the tools available to him if he believes that the oil market is being manipulated," Republican House Speaker John Boehner told reporters.

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The Secret Service has stripped 11 agents tied to a prostitution scandal in Colombia of their "Top Secret" clearances and taken away their badges and guns, an agency spokesman told Yahoo News on Monday.

"They've had their security clearances suspended pending the outcome of the investigation," Special Agent in Charge Edwin Donovan said by telephone.

The agents have been placed on a "Do Not Admit" list that bars them from Secret Service facilities and have turned in their service identification and firearms -- all steps resulting from having been placed on paid administrative leave, Donovan said.

The investigation could lead to the agents being exonerated and restored to their full status. But a law enforcement official said they could also be fired or even face criminal charges.

News of the revoked clearances came as the top U.S. military officer, Army General Martin Dempsey, said the Pentagon was "embarrassed" by the involvement of an unspecified number of military personnel in the scandal.

An undisclosed number of Secret Service agents with President Barack Obama at an international summit in Colombia have been relieved of their assignments and face an investigation over alleged misconduct, a spokesman for the Secret Service said late Friday.

Click image to view more photos (REUTERS/Claudia Daut)

The Associated Press, citing an anonymous tip, reported that the allegations involved prostitutes in Cartagena, the city hosting the gathering. The AP also said 12 agents were involved. The Washington Post cited the president of the Federal Law Enforcement Officers Association, Jon Adler, as saying that the allegations were tied to at least one agent being involved with prostitutes in Cartagena.

Secret Service spokesman Edwin Donovan declined to confirm that the conduct involved prostitutes.

"There have been allegations of misconduct made against Secret Service personnel in Cartagena, Colombia prior to the President's trip. Because of this, those personnel are being relieved of their assignments, returned to their place of duty,

Click image to see more photos. (AP/Carolyn Kaster)

On the eve of high-stakes talks with Iran, the White House on Friday signaled a willingness to consider giving Tehran economic incentives—but only after the regime takes "concrete steps" toward freezing its suspect nuclear program.

"We would certainly explore reciprocal actions that are responsive to concrete steps by the Iranians," said Ben Rhodes, President Barack Obama's deputy national security adviser for strategic communications.

"We'll be ready to reciprocate steps that they take, but again we'll have to see actions, not just words, from the Iranian government," Rhodes told reporters aboard Air Force One as Obama headed via Florida to a summit in Colombia.

[Related: Obama’s North Korea policy ‘absolutely not’ a failure, White House says]

His comments came with negotiators from the United States, Britain, France, Russia and China—the five permanent members of the U.N. Security Council—as well as Germany set to hold talks Saturday with Iran in Istanbul.

The so-called P5+1 want Iran to take actions to reassure the world that it is not seeking nuclear weapons under the guise of what it insists is a civilian atomic energy program.

Tehran denies the charges. But recent reports from the U.N. nuclear watchdog, the International Atomic Energy Agency (IAEA), have stoked concerns about Iran's refusal to bow to world demands that it freeze its uranium enrichment. Enrichment can be a key step toward building a nuclear weapon.

Rhodes set low expectations for the talks in Turkey—the first such face-to-face discussions in over a year.

The White House denied Friday that North Korea's rocket launch showed that President Barack Obama's efforts to engage the isolated country's secretive Stalinist regime had been a failure.

"Absolutely not," Ben Rhodes, the deputy national security adviser for strategic communications, told reporters aboard Air Force One as Obama headed from Washington to Florida, on his way to a summit in Colombia.

Mitt Romney said Thursday that the rocket launch, which Washington said was actually an attempt to test an intercontinental ballistic missile, reflected Obama's "incompetence" in dealing with the North Korean regime. Romney accused the president of having "emboldened the North Korean regime and undermined the security of the United States and our allies."

"First of all, what this administration has done is broken the cycle of rewarding provocative actions by the North Koreans that we've seen in the past," Rhodes countered, arguing that President George W. Bush had provided "a substantial amount of assistance" to the Hermit Kingdom and noting that Bush had removed Pyongyang from the list of state sponsors of terrorism.

"Under our administration we have not provided any assistance to North Korea," Rhodes said, adding that the Obama administration had imposed "unprecedented sanctions" on the isolated regime and made clear to that it would lose planned food aid if it went ahead with the launch. White House officials said late Thursday that the food aid was now on hold.

Click image to see more photos. (AFP/Brendan Smialowski)President Barack Obama's secretary paid taxes at a higher rate than he did in 2011 despite having a "substantially lower income," the White House said Friday, casting the disparity as an argument for Congress to adopt the so-called "Buffett Rule."

[Related: Your Top Tax Questions Answered]

"The president's secretary pays a slightly higher rate this year than the president on her substantially lower income, which is exactly why we need to reform our tax code and ask the wealthiest to pay their fair share," Amy Brundage, a White House spokeswoman, told Yahoo News by email.

Obama on Friday released his 2011 tax filings, showing that he paid $162,074 in total taxes on adjusted gross income of $789,674, an effective rate of 20.5 percent. The first couple paid $31,941 in Illinois income tax. Obama's secretary, Anita Decker Breckenridge, made $95,000 in 2011, according to the White House's public report on pay in the West Wing.

The president has been making the case for the Buffett Rule legislation that would raise taxes on the very richest Americans in order to ensure they do not pay a lower rate than middle-class filers. Obama has used the measure as a political cudgel to assault Mitt Romney, who has dismissed the proposal as a campaign gimmick.