The chance New York real estate developer Donald Trump will be the next president of the United States has gone from impossible to improbable to likely in the relative blink of an eye. Several recent national polls have him running even with or even ahead of former Secretary of State Hillary Rodham Clinton.

He's nipping at her heels in state polls, too. In New Jersey he's behind by four – 38 percent to 34 percent. They're tied in New Hampshire according to one poll, 44 percent a piece, and Trump is ahead in Oregon by two – 44 percent to 42 percent. Sure, it's early in the race, the voter screens may be unreliable and both candidates have a lot of ground to cover between now and their nominating conventions later in the summer. Nevertheless, the louder the liberals scream about Trump, the better he seems to do.

There are a lot of reasons for this. Serious people have put serious effort into explaining why Trump is doing so well while Clinton is comparatively in trouble. Whatever they may conclude, however, it all comes down to one thing: vision. He has it, she doesn't and the voters know it.

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Vision is the core concept underlying any campaign for office, especially the presidency. A candidate has to be able to explain quickly and right off the bat why he or she wants to be president. Trump can: He wants "to make America great again." Clinton can't, at least not persuasively enough to countermand her opponent's appeal to independents, swing voters and the working-class Americans in whose hands and ballots the power to pick the next president likely resides.

Clinton cannot campaign as a trustworthy leader or as an experienced pol. Her previous behavior as first lady and secretary of state leave these avenues closed off to her. She doesn't want to answer unflattering questions about her record, so she avoids them. The American voter won't let her have it both ways: They have grown far too cynical for that.

She also can't campaign promising to extend the policies of Barack Obama and the progressive turn the national electorate appeared to take in 2008. America remains a center-right nation. European-style socialism, with a small "s," may be catching on among the portion of the electorate that likes Vermont Sen. Bernie Sanders, but it's hardly mainstream. Not yet, anyway. Just about every credible independent national poll taken over the last six months has found only 25 percent of the country feels the United States is headed in the right direction. An astonishing two-thirds of those surveyed – and go ahead, pick your poll – believe this nation is on the wrong track. The next presidential contest is a change election that Clinton will not win if all she can do is promise four more years of what we've experienced over the last eight.

Trump's message, even if it is still only a basic outline with few details filled in, is both clear and resonating. Clinton's is ambiguous. That it's "her turn" – unless your name is Kennedy, Bush, Adams, Roosevelt, Taft or Romney, we Americans tend to eschew politicians with dynastic ambitions – is not a winning message, nor is it one grounded in the idea it is time for a woman in the Oval Office.

Her economic plan is a direct attack on what people are calling the sharing economy. She can run as the candidate promising to make equal pay for equal work a reality but that falls apart once anyone looks at the Clinton Foundation, where male executives make on average 38 percent more than the women. She can't run as a strong and effective voice to re-establish America's role in global peace and security without having to talk about Benghazi.

In short, she's run out of things to talk about. People can't explain what the country would look like after she is president for four years. She's failed to convey her vision of the future in any meaningful sense while Trump has gone about the business of owning it.