Donald Trump endorsed Mehmet Oz in the crowded Republican Senate primary.

In a statement Saturday evening, Trump said his decision was all about winning elections, and that he had formally endorsed the celebrity heart surgeon best known as the host of daytime TV's The Dr. Oz Show.

The Great Commonwealth of Pennsylvania has a chance to save America by electing Mehmet Oz to the United States Senate. He said it was like a poll when he was in television for 18 years. That means people like you.

In the May 17 primary, Oz was competing for the endorsement of Trump against David McCormick, whose wife served in the Trump administration. The two went to great lengths to win over the former president, who remains popular with the Republican base and has been wooed by candidates in primary races across the country.

At a conservative forum in Pennsylvania last weekend, the candidates were asked if they would like Trump to come to Pennsylvania and campaign for them.

Jeff Bartos, a real estate investor, said that was the easiest question to ask. Absolutely, yes.

The decision marks a disappointment for McCormick, who met with Trump last week and had hired a number of former Trump aides for his campaign. He topped a recent Fox News poll of Pennsylvania GOP primary voters, even though he was virtually unknown to voters.

Sean Parnell withdrew from the race after allegations of abuse from his estranged wife. The turnabout raised questions about the thoroughness of Trump's vetting process and whether the former president was bolstering candidates who might be able to win their respective primaries but fail in general elections that will determine which party controls the Senate.

This time, Trump made it clear that he wanted to win the election. He noted that Oz was a well-known quantity who has lived with us through the screen and has always been popular, respected and smart.

Mehmet Oz will be the one most able to win the General Election against a Radical Left Democrat looking to do unthinkable harm to our Country. Over the years, I have seen this many times. He said that they know him, believe in him, and trust him.

Trump told Oz that his wife was a big fan of the show.

Oz has a personal relationship with Trump.

In a recent interview, Oz said that he had first met Trump in 2004, when he asked him to use his golf course for an event. Trump agreed. After that, they saw each other at social events before Oz interviewed Trump about his health.

Trump has praised Oz for his positive treatment on the show and even said he should lose a couple of pounds.

McCormick has made inroads with party donors and officials in Pennsylvania and has gotten endorsements from former Trump administration officials. He had to work hard to become a pro-Trump candidate.

There are strong Republican establishment ties that go back to the days of President George W. Bush. Bush was a rival of Trump in the 2016 election.

That has led to charges that he is a globalist, a derogatory term used by Trump and others.

Oz has been attacked by the super PAC supporting him.

Oz's long career on TV and as a public personality were picked apart by the ads, which accused him of being a liberal. Oz is accused of being too Hollywood.

Oz is in the race for carpetbaggery. After living in New Jersey for two decades, he decided to run in Pennsylvania, where his in-laws live.

Some Oz critics, including Parnell, criticized Trump for his decision.

I have a lot of respect for President Trump. I was honored to have his endorsement. Oz is the antithesis of everything that made Trump the best president of my lifetime.