Richard Nixon was a crafty president, at war with his political enemies but inclined to carry out most of his battles behind the scenes. Donald Trump trumpets his grievances, using public lashings to diminish his enemies and nip at allies who anger him. Nixon began his second term in January of 1973 with support from nearly 70 percent of the American people. Mr. Trump’s public approval has never hit 50 percent, according to the Gallup poll. Nixon saw his support steadily erode as details of the Watergate scandal trickled out. Mr. Trump’s support has held steady despite a fire hose of accusations. His approval rating stood at a typical 43 percent when the House opened its impeachment inquiry on Sept. 24.

Ultimately, Nixon resigned after losing the support of his own party, while Mr. Trump is likely to survive a Senate trial as he runs for re-election with strong backing from his party. The difference between the two embattled presidents isn’t necessarily measured best by the severity of the accusations or the solidity of the evidence against them. Instead, factors unrelated to the facts are shielding Mr. Trump to a degree that Nixon would have envied. What are they? Here’s our assessment of how the two impeachment dramas played out:

PRESIDENTIAL CONDUCT

Perilous for Both Presidents

Then: President Nixon was accused of trying to unlawfully influence the 1972 election. On June 17, 1972, five burglars linked to the Committee to Re-elect the President broke into the Democratic National Committee headquarters in Washington’s Watergate complex. Though there is still debate about what the burglars were seeking, Nixon’s role in trying to cover up his campaign’s involvement became central to efforts to impeach him.

Nixon faced three articles of impeachment but quit before the House voted on them. One was for abuse of power for refusing to comply with congressional subpoenas, thus subverting the constitutional scheme of government. He was also accused of obstructing justice by, among other things, paying off the burglars to encourage their silence and making false and misleading statements to investigators and to the public. Nixon also faced a third charge — that he misused the I.R.S., F.B.I., Secret Service and other government agencies to violate the constitutional rights of citizens.