Republican presidential candidate Donald Trump records a segment for a news channel prior to a campaign rally, Wednesday, Dec. 16, 2015, in Mesa, Ariz. (AP Photo/Ross D. Franklin)

The rules governing presidential campaigns are being rewritten in fundamental ways for the 2016 election, and Republican front-runner Donald Trump is generating much of the change.

Trump, a billionaire real-estate developer, says he is largely financing his own campaign and not relying on big donors or special interests, which is unusual in itself. But he is also plowing new ground because he has based his effort so far not on paid advertising or a huge staff – which saves him money – but on free media. He has been able to generate endless news coverage in the mainstream media almost at will and is a huge presence on social media, including Twitter and Instagram.

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Trump's comments this week about former President Bill Clinton are a case in point. After Democratic front-runner Hillary Clinton strongly criticized Trump's history of making inflammatory remarks and what she called his sexist attitudes, Trump warned that she was walking on dangerous ground. Trump, who has 5.5 million followers on Twitter, tweeted that it's Bill Clinton, Hillary's husband, who actually has a history of anti-female behavior. He was referring to Clinton's impeachment by the House of Representatives in 1998 for lying about his affair with former White House intern Monica Lewinsky. The Senate acquitted Clinton in early 1999, concluding that the charges did not constitute an impeachable offense. But Trump says Bill Clinton's conduct will be fair game in the general election campaign if Hillary wins the Democratic nomination.

The news media have covered Trump's threats about Clinton extensively, making his warnings one of the biggest political stories of the week. And it was all based on a few lines that Trump wrote on Twitter. Democratic pollster Geoff Garin, who advises a political action committee supporting Clinton, told me, "Trump's use of social media is more to drive coverage than it is to organize and rally his followers. ... Nobody has used it as well as Trump." Adds Garin: "Any idiot can insult someone in 140 characters but up until now nobody's made that the signature of their campaign. Whenever Donald Trump insults someone, whether in social media or traditional media, it becomes a story."

Trump has selected targets, such as immigrants and China, that make him ever more popular with his core constituencies such as working-class white men and others who are fed up with the status quo and Washington's political elites, according to the opinion polls. And so instead of detailed policy papers and speeches, Trump has based his campaign on catchy one-liners and berating opponents and constituency groups he finds objectionable.

Evidence that all this is working came in a recent Tyndall Report that analyzed airtime on the main news programs of ABC, CBS and NBC. The 2016 election had received 857 minutes of coverage on all three networks  this year through Nov. 30, and Trump was the most covered candidate by far. He received 234 minutes of coverage, more airtime than the entire Democratic field. Hillary Clinton received 113 minutes. Sen. Bernie Sanders of Vermont, Clinton's main competitor for the Democratic nomination, got 10 minutes. Former Gov. Jeb Bush of Florida, who was considered the GOP front-runner at the start of the year, got 56 minutes.

Other candidates also are doing some unorthodox things. Sanders campaigns openly as a self-styled democratic socialist. This description was once considered too far to the left and anathema to most voters. But the anger in the electorate toward big corporations, greedy oligarchs and Washington insiders has generated for Sanders some of the biggest crowds of the campaign even though Clinton has a strong lead nationally in the polls.

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Clinton is also sounding more populist, saying she would champion the middle class as president and pledging to take on big, powerful interests. Clinton is also doing something she refused to do in her unsuccessful bid for the Democratic presidential nomination in 2008, which she lost to Barack Obama. She is campaigning on the basis of her gender as she seeks to become the first woman president of the United States. 

Several of the major campaigns have another attitude in common – contempt for the news media – that is being taken to new levels of intensity. They regularly tangle with or attack the media for being biased and for failing to understand the country and its concerns. Many Americans tell pollsters that they agree.

As of now, Trump is riding high, and his public relations strategy has been one of the biggest successes of the campaign so far. While the elites stew about his inflammatory rhetoric and his snarling persona, many everyday Americans have other ideas. The Gallup Poll finds that while President Obama is the most admired man among Americans today (with Hillary Clinton the most admired woman), there is a tie for second place. That's between Pope Francis and Donald Trump.