The Republican majority in Washington has vowed to bulldoze the legacy of President Barack Obama. Because Democrats — despite round-the-clock efforts this week in the confirmation votes of Betsy DeVos as education secretary and Jeff Sessions as attorney general — have yet to block any member of President Trump’s cabinet, Democrats might appear to have little hope of stopping the Republican juggernaut.

While Democrats are out of power, though, they are not out of options. Their tools are limited in the House. But archaic chamber rules grant Democrats considerable leverage in the Senate. By dragging their feet, sticking together and driving wedges between Republicans and Mr. Trump, Senate Democrats can focus attention on controversial parts of the president’s agenda and force Republicans to cast potentially unpopular votes.

In the House, a simple majority can end debate and bring matters to a vote. In the Senate, rules on debating and amending bills typically limit the ways the majority leader can advance a party plan, creating avenues for Democrats to gum up the works.

Those rules empower a cohesive minority in several ways. The majority leader routinely seeks unanimous consent on procedural matters, meaning that one senator can temporarily block the majority. As a former top Senate staffer recently observed, withholding consent is a sure way for Democrats to slow or stop Mr. Trump. Want to force committees to adjourn? Refuse consent when the leader wants to waive the rule that prevents committees from meeting beyond the first two hours of a Senate day. Want to delay votes for 30 hours? Refuse consent. If Democrats make sure to always have a senator available to dissent and Republicans don’t retaliate by adjusting chamber rules, such tactics can potentially secure concessions.