Maggie Haberman

Once again thumbing his nose at a time-honored tradition, Donald Trump said Friday that he does not believe voters have a right to see his tax returns, and he insisted it was “none of your business” when pressed on what tax rate he pays.

Trump said his supporters want him to run as a fiery populist outsider and to rely on his raucous rallies to build support through “word of mouth,” rather than to embrace a traditional, mellower and more inclusive approach that congressional Republicans will advocate in meetings with him on Thursday.

The national field director for Donald Trump’s campaign — who is a loyalist to Corey Lewandowski, the embattled campaign manager — resigned in a letter to Trump on Monday afternoon.

More than half of the record spending on negative advertising during the 2016 presidential primary has been directed at a single candidate, Donald Trump, a barrage that threatens to undermine his candidacy even as he continues to march toward the Republican nomination.

Trump ran afoul of conservative doctrine, with opponents of abortion rights immediately castigating him for suggesting that those who receive abortions — and not merely those who perform them — should be punished if the practice is outlawed.

Donald Trump, the Republican presidential front-runner, said that if elected, he might halt purchases of oil from Saudi Arabia and other Arab allies unless they commit ground troops to the fight against the Islamic State or “substantially reimburse” the United States for combating the militant group, which threatens their stability.

Alarmed by Donald J. Trump’s victories in seven states on Super Tuesday, Republicans desperate to sink his presidential bid are moving to battle him on two fronts.

If Trump’s merciless methods have seemed to help him so far, there could be a political downside over the long run. Several people he has targeted have said they would have difficulty supporting him in a general election.

In a rollicking day of spectacle, spite and scorn, Gov. Chris Christie of New Jersey declared his allegiance to Donald Trump and war on Sen. Marco Rubio, describing him Friday as desperate and unfit for the presidency.

Mainstream Republicans grappled on Sunday with Donald J. Trump’s sweeping victory in South Carolina as if cycling through stages of grief, with some in denial, some outraged and some accepting what now seems increasingly likely.

Fox News' decision to fight back this week after Trump demanded Fox remove Megyn Kelly from its panel of moderators at a debate Thursday sent the already unconventional Republican race for president into uncharted territory just days before the first critical contest in Iowa.

Donald J. Trump and Fox News stared each other down on Tuesday over his demand that news anchor Megyn Kelly be dumped from moderating Thursday’s debate, the last before Monday’s Iowa caucuses.

Galled by Donald Trump’s dominance of the Republican field, and troubled by Hillary Clinton’s stumbles and the rise of Sen. Bernie Sanders of Vermont on the Democratic side, Michael R. Bloomberg has instructed advisers to draw up plans for an independent campaign in this year’s presidential race.

The backing of Palin, the former Alaska governor and vice presidential nominee, provides Trump with a potential boost less than two weeks before the Iowa caucuses.

As rumors swirled Tuesday that Sarah Palin, the 2008 Republican vice presidential nominee, would endorse Donald Trump in Iowa, the former Alaska governor posted on Twitter a link to a comment from her daughter Bristol slamming Sen. Ted Cruz.