Global currency devaluation efforts are hurting the U.S. and costing American jobs, Republican presidential front-runner Donald Trump told CNBC in a wide-ranging interview Thursday. "You see [devaluations] almost everywhere except for the United States," he said. "We do nothing about it. We just sit back and let everybody do it. And that's getting to be very dangerous." To combat currency debasements, the U.S. should tax overseas products to level the trade playing field, he said. "They're taking advantage of our country. We don't have strong leadership. We don't have strong economic leadership at all."

On one hand, Trump ramped up his blame-China rhetoric, calling Beijing "the grandmaster of all" when it comes to currency manipulation and free trade cheating. At the same time, he said: "My relationships with China are fantastic. I have great relationships and business relationships with China. Even those people are saying they can't believe what they are getting away with." "We can't let the world take advantage of us from an economic standpoint. And that's what they are doing," he contended, calling for a stop to efforts by other countries to "suck more blood out of the United States." Trump added that he supports the idea of free trade if the right people are negotiating the terms so that both sides benefit. "We are being out-negotiated at every corner."

Corporate tax code "structurally wrong"

Pointing to Pfizer's planned tax inversion takeover of Irish drugmaker Allergan, he said the trend of American companies merging and re-corporating overseas to avoid paying higher U.S. business taxes is a sign of something "structurally wrong." The U.S. needs to keep American companies from moving, and it's worse than the media is reporting, Trump said, arguing his tax ideas would incentivize firms to stay put, while cutting waste and spurring the economy.

'Elites' should stop working against me

Trump also said establishment Republicans should get on board with what the voters want, because Americans turned out in droves to support his candidacy. He said he's surprised that party "elites" are working against him. "You would think that Republicans would say, 'Wow, we have hit pay dirt. This is incredible. Let's embrace Trump and let's go and win the election.'" "I am a unifier. I am not a divider. When things settle down ... I think people will see that," Trump said in the phone interview on "Squawk Box," ahead of Thursday night's debate in Miami and Tuesday's key primaries in Florida and Ohio. The GOP presidential front-runner said if he were not chosen as the party's nominee, the Democrats would keep the White House — thus ensuring more liberal Supreme Court justices. He said rival Texas Sen. Ted Cruz has no chance in a general election: "He'll never win states that you have to ... because of his views on things." Trump said he probably hasn't been as nice or as "politically correct" as he would have liked in the race, because of the cut-throat nature of the primary process, which started out with 17 candidates. "They were very tough on me. And I was tougher on them," he said. "I have actually taken my positives up a lot, but it's hard when you're in a battle like this."

Next up: key primaries in Florida and Ohio

In the lead-up to Tuesday's 99-delegate, winner-take-all Florida primary, Trump leads Florida Sen. Marco Rubio by 17 percentage points in the lawmaker's home state, according to the RealClear Politics polling aggregator. Rubio's support has been recently fading — exemplified by a string of weak performances in the latest nominating contests. Ohio, with 66 winner-take-all delegates up for grabs, also holds its primary Tuesday, and Trump has a narrow 2.5 percentage point lead over Ohio Gov. John Kasich there, according to the latest polls. "I think I have a good shot in Ohio. And I have a much better than good shot in Florida," Trump predicted, saying he created many jobs in Florida through his business ventures and owns a lot of property there.

Kasich, with billionaire Wall Street backers Stanley Druckenmiller and Ken Langone, hopes to win his home state and jumpstart his struggling campaign. Kasich is dead last in the delegate count, behind Trump, Cruz and Rubio. Trump said it's too early in the race to talk about a vice presidential running mate. Speculation has swirled around whether Chris Christie might be on the short-list, after the New Jersey governor and former GOP presidential candidate endorsed Trump last week. "Chris is a good man," Trump said. "[But] it's too early." He added he'd pick "somebody very good" when the time is right. Trump refused to speculate on what a two-man race with Cruz might look like. "Who knows what happens. It's politics. It's crazier than business."

'Do what's right' on Clinton email flap