Why haven’t efforts to impeach President Trump gained Watergate-style momentum? The lack of energy has created a sense of bafflement and disappointment among some of the president’s most determined adversaries. But there are some simple reasons for it. Here are three:

1) The facts are different. In Watergate, the underlying crime was a break-in at Democratic National Committee headquarters, perpetrated by burglars paid by President Nixon’s re-election campaign. The scandal proceeded from there. In Trump-Russia, the underlying crime was the hacking of the DNC’s and John Podesta’s emails — a crime committed by Russians in Russia. Special counsel Robert Mueller, who indicted a number of Russians and Russian entities for their actions, spent two years trying to find conspiracy or coordination between the Russians and the Trump campaign. He failed.

That single fact has shaped every other aspect of the Trump-Russia affair. In Watergate, the cover-up flowed from Nixon’s desire to conceal his campaign’s involvement in the break-in and other political dark acts. It formed the bulk of the obstruction of justice case against Nixon, which in turn served as the basis for articles of impeachment.

In Trump-Russia, Mueller did not charge, although he clearly suggested that Trump obstructed the investigation of an event — conspiracy/coordination — that did not happen. That meant the simplest, most plausible motive for obstruction — Trump, knowing he was guilty, tried to cover up his campaign’s conspiracy with Russia — was off the table.

2) The press is different. Just as the facts of Trump-Russia are quite unlike Watergate, so the media environment of 2019 is quite unlike what existed in 1974. Back then, there were three 30-minute broadcast network newscasts: CBS, NBC and ABC. There were two big newspapers, The New York Times and The Washington Post, and TV network executives sat down each day, within a few blocks of each other in Manhattan, to produce newscasts that basically illustrated the papers’ latest stories. There was no internet, no cable news, no podcasts, no social media and no talk radio. Nixon, even if he had had strong defenses, faced a solid wall of media opposition.

3) Congress is different. Differences in the facts of the cases and differences in the media’s ability to report those facts have had a profound effect on lawmakers. They’re better informed, if they want to be, and can make a better defense of the president of their party. And having a significant number of constituents supporting the president makes representatives more likely to support him, too. (Unlike today, in 1974 opposition party Democrats controlled all of Congress.)

So this is a new world. It is perhaps not surprising to hear Democrats wish they could somehow turn today’s Trump-Russia affair into yesterday’s Watergate.

Others believe they just need time. It took Watergate years to grow big enough to oust Nixon, they say. But the break-in was in June 1972, and Nixon resigned in August 1974 — a period of two years and two months. In Trump-Russia, the FBI began its investigation nearly three years ago, in July 2016. The Senate began investigating in January 2017. And Mueller took office in May 2017. It’s been a long time.

Trump-Russia could go longer still, and it would not change the basic facts of the case. It is simply a different case in a different world. Try as they might, the president’s opponents can’t make it 1974 again.