David Axelrod, formerly the chief strategist for President Barack Obama, took issue earlier this month with the Democrats’ simmering desire to remove President Donald Trump from office. “Dems should NOT commit to impeachment unless & until there’s a demonstrable case for one,” he wrote on Twitter. “It is not just a matter of politics. It’s a matter of principle. If we ‘normalize’ impeachment as a political tool, it will be another hammer blow to our democracy.”



That drew a rebuke from Tom Steyer, a liberal billionaire currently bankrolling an aggressive ad campaign urging Americans to rally behind Trump’s impeachment. “Let’s be clear: Trump has already committed 8 impeachable offenses,” he tweeted in response to Axelrod. “What are we waiting for?”

Steyer’s question makes impeachment seem simple and obvious. History proves otherwise. Congress has never removed a president from office, so there’s no clear road map for successfully doing so. But there are lessons from the past about how such efforts can fail.

Andrew Johnson’s impeachment in 1868 took place amid Reconstruction and just after the United States had emerged from a civil war. For all its problems today, modern American politics is nowhere near as tumultuous. President Richard Nixon would’ve almost certainly been impeached by the House and likely convicted by the Senate but for his resignation in 1974. If Trump finds himself in similar circumstances, it’s hard to see him stepping down rather than fighting it out.

That leaves only the case of Bill Clinton, who was impeached by the House for perjury and obstruction of justice and acquitted by the Senate on both counts. That draining, fractious battle two decades ago demonstrates some of the risks for campaigns to oust Trump today.