Republican presidential candidate, Sen. Marco Rubio, R-Fla. smiles while speaking during an event hosted by the Foreign Policy Initiative, Friday Aug. 14, 2015, in New York. (AP / Tina Fineberg )

NEW YORK -- Republican presidential candidate Marco Rubio vowed Friday to roll back the Obama administration's new policy on Cuba on his first day in office, casting the plan to normalize relations with the island nation as a dangerous shift that gives the Castro regime international legitimacy and more resources to repress its people.

Photo by CHARLIE NEIBERGALL / AP

Republican presidential candidate former Florida Gov. Jeb Bush talks with fairgoers Friday during a visit to the Iowa State Fair in Des Moines.

Photo by CHARLIE RIEDEL / AP

Republican presidential candidate Carly Fiorina at the Starboard Market Friday, Aug. 14, 2015, in Clear Lake, Iowa.

Photo by JIM COLE / AP

Democratic presidential candidate Hillary Rodham Clinton shakes hands during a campaign stop at River Valley Community College Tuesday, Aug. 11, 2015, in Claremont, N.H.

In a blistering speech Friday to the conservative-leaning Foreign Policy Initiative in New York, delivered the same day Secretary of State John Kerry reopened the U.S. Embassy in Havana, the Florida senator charged that President Barack Obama's diplomacy -- on Cuba and the recent Iran nuclear deal -- provides evidence of "every flawed strategic, moral and economic notion" that has driven the Democratic president's foreign policy.

"He has been quick to deal with the oppressors but slow to deal with the oppressed," Rubio said. "And his excuses are paper-thin."

The Cuban-American lawmaker has made foreign policy a centerpiece of his campaign for president and a focus in his first five years in Congress, where he has served as a member of the Senate Foreign Relations Committee.

In the speech, Rubio said he would put Cuba back on the list of state sponsors of terrorism and require the Castro regime to "carry out meaningful political and human-rights reforms" or lose its new diplomatic and economic benefits with the U.S.

The Obama administration has said it is normalizing ties with Cuba after more than 50 years of hostility because dealing directly with Cuba over issues including human rights and trade is far likelier to produce democratic and free-market gains over the long term.

In his speech, Rubio vowed to reimpose the economic sanctions on Iran that the U.S. and other world powers agreed to lift in exchange for curbs on Tehran's nuclear program.

Any talks to come afterward must result in a deal that terminates Iran's nuclear program, he said, and also would be tied to "Iran's broader conduct, from human-rights abuses to support for terrorism and threats against Israel."

Opposition to the Iran nuclear deal is universal among the Republican candidates for president. Congress will vote on the agreement in September.

Elsewhere on the campaign trail, Jeb Bush was greeted at the Iowa State Fair on Friday by the top three Republicans in Iowa.

U.S. Sens. Charles Grassley and Joni Ernst welcomed the former Florida governor to the fair early Friday, and Gov. Terry Branstad joined him to flip pork loins on the grill at the Iowa Pork Producers tent later in the morning.

"We're finding out that Gov. Bush is working the state very hard," said Grassley, who hasn't endorsed a candidate. "His competitors better keep up with him."

Bush's tour included snacking on a deep fried Snickers bar, sampling pork chops on sticks and appearing on the political soapbox -- where he got pinged on Iraq, capping a week in which he focused heavily on foreign policy.

Asked whether he was "all-in" for the leadoff caucus state, Bush stressed that he would be "competitive."

"Last time around there were candidates that were winning at this point that never even made it to the starting line," Bush said.

During his 20 minutes on the candidate soapbox hosted by The Des Moines Register newspaper, Bush stressed his executive experience and said he supports education standards created by states. He also gave out an email address to the crowd of hundreds and said he was committed to transparency.

Fellow GOP candidate Donald Trump and Democratic candidate Hillary Rodham Clinton plan to visit the fair today.

In other news from Iowa campaigns, Republican presidential candidate Carly Fiorina said parents shouldn't be required to vaccinate their kids.

"When in doubt, it is always the parent's choice," she said during a town hall event Thursday in rural Iowa. "When in doubt, it must always be the parent's choice."

Fiorina recounted how her daughter was "bullied" by a school nurse when deciding whether to give her own child the HPV vaccine.

Later, Fiorina clarified her statements for reporters.

Fiorina said that while "highly communicable diseases" are one thing, schools should not be able to mandate "these more esoteric immunizations."

On the Democratic side, four major candidates met at the Surf Ballroom in Clear Lake for the annual Wing Ding, a Democratic fundraiser. Clinton, U.S. Sen. Bernie Sanders of Vermont, former Maryland Gov. Martin O'Malley and former Rhode Island Gov. Lincoln Chafee all spoke.

Clinton offered a fierce defense of her handling of the 2012 Benghazi attacks and her use of a private email server as President Barack Obama's secretary of state, dismissing the controversies as "partisan games."

"They'll try to tell you it's about Benghazi, but it's not," said Clinton, referring to Republican-led congressional inquiries. "It's not about emails or servers, either. It's about politics."

Sanders received loud cheers when he pointed to his opposition to the Keystone XL pipeline and his vote in the Senate against the Iraq War.

Sanders, whose recent appearance at a Seattle event was disrupted by activists with the Black Lives Matter movement, also took steps to emphasize his civil-rights record.

"No one will fight harder to end racism in America," he said.

O'Malley referred to a list of progressive proposals he would pursue if elected president, saying his years as the mayor of Baltimore and Maryland's two-term governor were about "action, not words."

"In tougher times than these, Franklin Roosevelt told us not to be afraid. In changing times, John Kennedy told us to govern is to choose," O'Malley said. "I say to you, progress is a choice."

Chafee took aim at Jeb Bush's recent critique of Obama's handling of Iraq, saying, "What kind of neocon Kool-Aid is this man drinking?"

Clinton kicked off her weekend of campaigning in Iowa by expanding on proposals for more quality child care on college campuses and additional scholarships to help students who are parents.

Information for this article was contributed by Sergio Bustos, Emily Swanson, Catherine Lucey, Ken Thomas and Scott Bauer of The Associated Press; by John McCormick of Bloomberg News; and by Christopher Ingraham of The Washington Post.

A Section on 08/15/2015