But Trump's analysis of current public polls is preposterous. In the RealClearPolitics.com average of recent polls, Trump trails Clinton by 6 points, 47 to 41 percent. Ted Cruz, in contrast, leads Clinton 46 to 45 percent.
Ex-candidate Marco Rubio and splinter candidate John Kasich have been running even better. All at least equal the 46 percent that is the lowest percentage won by either party's nominee this century. Against each of them Clinton falls short of that.
Trump's poll performance is not just a momentary blip. In 49 polls conducted matching him against Clinton starting last May, Trump led her in four, tied her in two and lost to her in 43.
Since the Feb. 25 debate, when Cruz and Rubio (finally) started pummeling him, Trump's losing margin has increased from 2 percent to 6 percent. His current 41 percent is his lowest showing in the RCP average since last August, when people were just starting to seriously contemplate his candidacy. Polls typically show 60-plus percent of voters with unfavorable feelings toward him, even worse than Clinton's 50-plus percent unfavorable rating.
Trump's standing could decline further if and when he is nominated. Then the mainstream media -- which has been giving him lavish coverage and acceding to his unusual demands for telephone interviews and non-mobile cameras -- will likely join the Democrats in unleashing attack after attack. That probably won't help!
Trump's weakness is confirmed by polling in the dozen target states whose votes will, if current patterns hold, determine the outcome in November. Trump trails Clinton in RCP averages in 11 of the 12, including North Carolina, which Mitt Romney carried in 2012. The exception is Colorado, in a single poll conducted last November, in which Cruz still ran stronger.
What about Trump's argument that he has brought new people into the electorate? He's right that Republican turnout (19.5 million) is way up and exceeds Democratic turnout (14.6 million) for the first time in a year when both parties have had protracted contests.
By no means have all first-time primary voters gone for Trump. But let's concede that current polling tends to produce an electorate whose composition resembles that of 2012 and entertain the possibility that this won't be the case in 2016.
Black turnout and Democratic percentage are likely to fall, with the first black president off the ballot. Young voters' aversion to Clinton, evident in Bernie Sander's 80-plus percent among under-30s in exit polls, could sharply reduce millennials' Democratic margin. The proportion of seniors -- a good demographic group for Trump -- is rising as the baby boomers age.
If you use the RCP interactive tool and adjust 2012 black turnout down by 10 percent and white turnout up 3 percent, and further adjust the Democratic percentages down 4 points among blacks and up 3 points among whites, you come out with a Republican popular vote and Electoral College lead -- even assuming the Republican does as badly with Hispanics and Asians as Romney did.
That would look more like the off-year electorates that gave Republicans 51 and 52 percent of popular votes for the House of Representatives in 2010 and 2012. It would look like an electorate expanded with the new voters predicted by the two candidates -- Trump's left-behind angry whites, Cruz's evangelical Christians. Both groups have shown up disproportionately in Republican primaries and caucuses so far.
But you can expand the electorate all you want, and if you still have a product that 50 percent of the voters won't buy, you lose the election. The addition of new voters might nudge Trump's unfavorable numbers down to 60 percent. But that's still a losing number, since Clinton seems to be holding nearly 90 percent of Democrats, although one-third don't consider her honest or trustworthy.
Some may believe that Trump's favorable numbers could improve and make him more competitive. That hasn't happened so far. His celebrity helped him corral a lot of votes early, and he's held on to them. Exit polls show his voters have been committed for months, with late deciders going mostly to other candidates.
Trump has won 37 percent of Republican votes and is regarded unfavorably by more than 60 percent of general election voters. It's hard to get from there to 270 electoral votes!