This will be the most contentious, most bitter, most polarizing and most unappealing race for president since James G. Blaine and Grover Cleveland competed in 1884. But it may be the least ideological presidential campaign since 1820, when the Federalists put forward a vice presidential candidate but couldn't even find a presidential nominee.

This is the most significant aftereffect to emerge from the two major parties' nomination fights that, ironically, were far more ideological than usual. The Republicans fought fiercely over which candidate was the most authentically conservative. The one who wasn't conservative at all won. The Democrats fought just as vigorously over who was the most progressive. The one who essentially adopted her rival's positions on the issues that most animate party activists -- climate change, Wall Street, college financing -- is the presumptive Democratic nominee.

This isn't to say that former Secretary of State Hillary Clinton and Manhattan businessman Donald Trump haven't taken some clear stands, particularly in the fractious debates that won so much public attention. We know, for example, which one would build a wall at the Mexican border and which one would try to tear down walls.

But these two likely nominees are peculiarly unideological, and the profiles they will advance in the autumn represent dramatic drifts from their roots.

Trump is the ultimate in un-ideology. He has advanced more profile than program, more a general way of looking at the world than a program for dealing with the world. Even some of his supporters agree that the Trump platform -- a phrase that overstates the coherence of his comments -- doesn't account for the complexity of modern Washington, which may be shaped by personality but is regulated by the separation of powers and checks and balances.

Some presidents can't control a State Department of their own party let alone a Congress of their own party. At the very least, Trump would face real hostility on Capitol Hill and contempt and resistance from the government bureaucrats he has ridiculed for months.

Simple nostrums -- we can thank Warren G. Harding for introducing that word into our political lexicon -- have powerfully affected American elections before: "Let's get America moving again" (John F. Kennedy, 1960), "Had enough?" (Republican congressional campaign, 1946), and "He kept us out of war" (Woodrow Wilson, 1916).

But behind each of them were far more specifics than the foundation on which "Let's make America great again" is built. All three of those old slogans -- plus the "Get the government off the backs of the American people" offered by Ronald Reagan in 1980 -- carried far more ideological weight than anything Trump has said.

For her part, Clinton may have more policy positions, but her ideology still lacks strong definition, particularly when compared with Sen. Bernie Sanders, who will not control the Democratic convention but surely has controlled the Democratic conversation. To an astonishing degree for a front-runner who seemed at the start to face little credible opposition, the Clinton campaign has been reactive rather than proactive.

Indeed, it is hard to recall any likely nominee being shaped so definitively by a challenger who never had a plausible chance of prevailing at the convention than Clinton has been by Sanders. It is as if the campaign of former Gov. Jimmy Carter of Georgia -- a far less likely nominee in 1976 than Clinton 40 years later -- allowed his message to be shaped by former Sen. Fred Harris of Oklahoma, whose New Hampshire campaign announcement on Jan. 11, 1975, could be uttered word for word by Sanders today:

"Privilege is the issue. It prevents full employment and fair taxes. It drives up prices and corrupts democracy."

Clinton does stake out strong positions, and she has a record. But those positions have changed with the seasons in American politics.

She was a "Goldwater girl" in 1964, which might be dismissed but for the fact that she was 17, not 11, when Goldwater ran, and if she hadn't said as an adult that "my political beliefs are rooted in the conservatism that I was raised with."

By the time she was 21 she had turned left, though in a remarkable speech at her 1969 Wellesley College commencement she opened, "I find myself in a familiar position, that of reacting, something that our generation has been doing for quite a while now," and added: "There's a very strange conservative strain that goes through a lot of New Left collegiate protests that I find very intriguing ..."

Conservatives are furious with Trump, whom they do not consider as one of their own, so much so that many rebellious Republicans speak of their party as being "in ruins." The phrase belongs to National Review writer David French, who adds:

"A minority of its primary voters have torched its founders' legacy by voting for a man who combines old-school Democratic ideology, a bizarre form of hyper-violent isolationism, fringe conspiracy theories and serial lies with an enthusiastic flock of online racists to create perhaps the most toxic electoral coalition since George Wallace."

Some conservatives won't attend the Cleveland convention and others won't vote for the nominee of their party -- dangerous for a party whose last presidential nominee won 93 percent of the Republican vote and still lost the election.

Nevertheless, a lack of ideology is a badge of honor for some backers of Trump, who has in the past donated to the campaigns of Clinton, Democratic Sens. Harry Reid of Nevada and the late Edward M. Kennedy of Massachusetts, and Rahm Emanuel, now Chicago's mayor. "There's going to be a moment in the Trump campaign," says Monica Morrill, a founder of the Somerset County, Pennsylvania, Republican Women's Committee, "when he transcends ideology."

But he is not alone. Clinton's ideology is so fuzzy that this month a piece appeared on the Huffington Post titled: "Hillary Clinton Is a Progressive Democrat, Despite What You May Have Heard."

Clinton, a former first lady, senator and secretary of state, has been in the public eye for at least 24 years. Take the year 1920, when Franklin Delano Roosevelt was the Democratic nominee for vice president, as the starting date for his prominence. Add 24 years and you come to the year 1944, when he ran for his fourth term. No one doubted FDR's ideology.

By David Shribman

NEA Columnist