Businessman and Republican presidential candidate Donald Trump speaks to supporters during a back-yard reception in Bedford, New Hampshire, June 30, 2015. REUTERS/Dominick Reuter

Has Donald Trump ever been wrong about anything? (Also, does he ever cry? Has he ever had self-doubt? Has he ever lay in bed awake at night crippled with anxiety?)

Perhaps no presidential candidate has the self-confidence he does, even in the face of some glaring flip-flops on his political positions. Where lesser candidates would dodge questions about why they've changed their mind or give a focus-group-tested line about how they evolved, Trump doesn't admit to ever having a different opinion.

He loved Hillary Clinton; now he thinks she's the worst. He was very much in favor of abortion rights before he opposed them. And he might be running as a Republican today, but he was once a registered Democrat who called for legalizing drugs, a massive one-time 14.25 percent tax on the wealthy and staying out of wars that didn't present a "direct threat" to the U.S. In many ways, he's been to the left of Clinton and even Bernie Sanders on some issues.

But in Trump's world, there is no truth but now. Here are some of his most glaring flips (or convenient evolutions):

Abortion

Then: On "Meet The Press" in 1999, Trump said he was "very pro-choice." "I hate the concept of abortion," he said. "I hate it. I hate everything it stands for. ... but I just believe in choice."
Now: In an interview with Bloomberg Politics in January, Trump said, "I'm pro-life and I have been pro-life." He said he believed there should be exceptions in cases of rape, incest or the life of the mother.

Guns

Then: In Trump's 200 book "The America We Deserve," he wrote that he "generally" opposed gun control but supported an assault weapons ban and a longer waiting period to purchase a firearm.
Now: At the 2015 NRA-ILA Leadership Forum, Trump said if he became president, "the 2nd Amendment will be totally protected." He told the Web site Ammoland he does "not support expanding background checks" and said current background checks "don't work."

Healthcare

Then: In an interview with Larry King in 1999, Trump said he was "very liberal when it comes to health care" and that he believes in "universal healthcare."
Now: During his announcement, he called Obamacare "a disaster called the big lie" and said the deductibles were so high they were "virtually useless."

Hillary Clinton

Then: Either Trump or his son donated to Clinton in 2002, 2005, 2006 and 2007, he invited her to his 2005 wedding in Florida, where she sat front row, and he's donated at least $100,000 to the Clinton Foundation. He also said in an appearance on the Howard Stern show in the mid-2000s that she was a fantastic senator.
Now: On NBC on Wednesday, he called Clinton "the worst secretary of state in the history of our nation" and said she would be "a terrible president."

Party affiliation

Then: Trump changed his party from Republican to Independent Party in 1999, and switched again to Democrat in 2001.
Now: Has been a registered Republican since 2009.

There are also some flips which haven't necessarily been from left to right.

Jeb Bush

Then: In Trump's 2000 book "The America We Deserve," he called Bush "a good man," "bright, tough and principled," and "exactly the kind of political leader this country needs now and will very much need in the future."
Now: On Fox News's "On The Record" this week, he called Bush "pathetic" for his support of Common Core, said his immigration views were "baby stuff."

Press availability

Then: Trump wrote in his 1990 book "Surviving At The Top" that he had been "burned too many times by reporters" and didn't believe in being available for the media anymore.
Now: He grants more interviews than anybody else -- including to the major TV stations on Wednesday and this new interview with the Post publish today and titled, "Trump vows long campaign, won't commit to backing GOP nominee."