MIAMI — In the heat of the Republican presidential primary, Marco Rubio called Donald Trump a "con man." And he doesn't take it back.

"I've stood by everything I ever said in my campaign," Rubio told the Miami Herald editorial board Monday.

But Rubio still supports Trump for president. In fact, Rubio insists, Trump is partly why he reversed himself and chose to run for the U.S. Senate again.

"We're in a different place now. Now we have a binary choice _ not a choice between 15 people or 12 people. There are two people in the world that are going to be the next president, either Donald or Hillary" Clinton, he said. "In our republic, while the presidency is powerful, there is a balance of power in this country, and a significant amount of it resides in the United States Senate. It's one of the reasons why I seek to run again."

Rubio rejected the idea that on foreign policy, one of his signature areas of expertise, his views align more with Clinton's than Trump's.

"I disagree with many of her foreign-policy positions," he said, rattling off a list of criticisms on how the Obama administration handled Russia, ISIS, the Syrian civil war, Libya after the Arab Spring and the Iran nuclear deal.

Rubio claimed ignorance of political and financial ties between Trump's campaign manager, Paul Manafort, and Russians who pushed for the invasion of Crimea. Asked if he'd accept the position of secretary of state — Clinton's former job — Rubio said no.

"I'd rather stay in the Senate," he said. "Not that the secretary of state is not an important job, but there's more work to be done in the Senate at this point, from my perspective and my view."

Rubio wouldn't rule out another presidential run of his own, either in 2020 or 2024. He maintained that returning to the Senate wouldn't be the best way to seek the White House again, though some of his advisers have privately suggested precisely the opposite.

"I've basically gotten into one of the toughest races in the country, on almost the very last second possible, in an environment where I don't control what's happening at the top of the ticket," Rubio said. "The easier thing for me to have done — in fact, what I was thinking about, is running again in four to eight years — is just to step out of politics, stay engaged and involved and run again."

Instead, he's a Senate candidate once more, against a single primary challenger, millionaire Sarasota developer Carlos Beruff. Rubio has hardly acknowledged the existence of Beruff's campaign and didn't mention him once Monday. Polls have shown Rubio comfortably ahead of Beruff leading up to the Aug. 30 primary; Beruff has accused the Republican Party of Florida of taking sides in the primary by inviting Rubio to the party's field-office openings across the state.

Rubio still leads the top Democratic candidate, U.S. Rep. Patrick Murphy, though a Quinnipiac University poll released last week showed the Republican's big advantage disappearing — which the poll's director blamed on Trump's detrimental effect on down-ballot candidates. Trump gave Rubio a shout-out at a Sunrise, Fla., rally last week, referring to him as "Marco, who we are totally supporting, and who is totally supporting us."

Trump and Clinton have been running neck-and-neck in Florida, with Clinton slightly ahead in polling averages. The most recent state voter-roll statistics suggest trouble for Trump, as the number of black and Hispanic voters who typically vote Democratic has increased faster than the number of non-Hispanic white voters.

Florida primary voters have been able to cast ballots by mail for two weeks, and early in-person polls opened Monday in Miami-Dade County. Rubio, trailed by TV cameras, voted in his hometown early Monday afternoon. About a dozen supporters at the West Miami Community Center met him with chants of, "Marco!"

From reporters, Rubio got more questions about Trump — including about the nominee's thin Florida ground effort.