Hillary Clinton's shadow loomed large on the Sunday talk show circuit as the political world prepared for her long-awaited formal entree into the 2016 presidential race. GOP opponent Rand Paul questioned the Clinton Foundation's ties to Saudi Arabia while John Kerry and New York Mayor Bill de Blasio, a former Clinton campaign manager, both declined to endorse the candidate just yet.

Rand Paul

Asked about potential debates with Clinton, presidential hopeful Sen. Rand Paul, R-Ky., said he would “treat her with the same respect I would treat a man.” Acknowledging his reputation as a stubborn opponent, Paul told CNN's "State of the Union" it would be “a sexist sort of response to say, ‘Oh my goodness she deserves not to be treated as aggressively because she’s a woman.’”

Later in the day Paul said in an interview on CBS’ “Face the Nation” Clinton’s popularity with women was at odds with gifts the Clinton Foundation has received from “Stone Age sort of regimes that really abuse the rights of women.” Saudi Arabia has donated tens of millions of dollars to the Clinton Foundation.

Other Republicans

Paul wasn’t the only Republican to pile criticism on Clinton. Mitt Romney, 2012's GOP standard-bearer, said Clinton is “just not trustworthy” in an interview on “Fox News Sunday.” On CBS’ “Face the Nation,” Republican National Committee Chairman Reince Priebus sounded a similar note, casting Clinton as "someone the American people can't trust.”

Former Arkansas Gov. Mike Huckabee called Clinton a “formidable candidate” on ABC’s “This Week,” but suggested her proximity to President Obama would raise difficulties. Announced presidential contender and former Florida Gov. Jeb Bush released a video Sunday explicitly linking the two Democrats. “We must do better than the Obama-Clinton foreign policy,” Bush said, blaming the two for “failed, big-government policies.”

Bill de Blasio

New York City Mayor Bill de Blasio, a progressive Democrat, punted on endorsing the presumptive candidate. “I would say this about any candidate, until I see an actual vision of where they want to go,” the mayor said of Clinton on NBC’s “Meet the Press.”

“We need to see the substance,” he said.

De Blasio managed Clinton’s 2000 Senate campaign but was reportedly shouldered aside in the crucial last months of the contest. In the last year de Blasio lobbied unsuccessfully to have the high-profile 2016 Democratic National Convention held in Brooklyn. His consolation prize: Clinton will reportedly base her campaign in Brooklyn Heights.

John Kerry

Secretary of State John Kerry, who has had his hands full with Iran and Cuba, also declined to endorse Clinton Sunday. “As you know, the secretary of state, happily, is able to not be involved in the presidential hurly burly,” Kerry said on ABC’s “This Week.”

Kerry also defended the provisional agreement with Iran over nuclear weapons and the administration’s moves to thaw diplomatic relations with Cuba. On NBC’s “Meet the Press,” Kerry was asked about anonymous reports he had suggested Obama take Cuba off the official list of state sponsors of terror. Kerry neither confirmed nor denied the rumors.

On the topic of Iran, Kerry disputed charges, made by Iran's Ayatollah Khamenei and repeated by Sen. John McCain, R-Ariz., U.S. diplomats had oversold the preliminary nuclear deal. Iranian officials have characterized aspects of the deal in ways that differ with reports from the American envoy, specifically regarding to how quickly sanctions would be lifted and the extent of nuclear research that would be permitted.

Kerry said he stood by “every fact that I have laid out” on the provisional Iran deal. 

Robert Menendez

New Jersey Sen. Robert Menendez defended himself Sunday against allegations he had accepted illegal gifts from a Florida ophthalmologist. “I know I will be vindicated and we will win,” he told Fox News.

Menendez was hit with a federal indictment April 1 for allegedly helping Dr. Salomon Melgen obtain visas for girlfriends. The Justice Department also accused the Democratic senator of lobbying the Obama administration for Medicare changes that would directly benefit Melgen.

Menendez has emerged as a staunch opponent of the administration’s evolving Cuba policy. The embattled senator resolved to fight Obama on the matter, despite his ongoing legal battles. “I will not be silenced,” Menendez said.

In other news…

CBS political director John Dickerson will take the helm of “Face the Nation,” replacing that show’s longstanding host Bob Schieffer. Dickerson, a Washington native and veteran political reporter, has made 83 previous appearances on the show.