The effort has been described by one lawmaker as “organic.” But the goal is clear: the lawmakers are hoping to build a critical mass of members that will force Pelosi to choose between defying the majority of her own caucus or moving forward with a process of removing the president from office—a step that has not been taken on in more than 20 years.

To do so, pro-impeachment members have been setting up meetings with other Democrats over the past week—and plan to do so over the next few as well—to try and sell them on the merits of impeachment proceedings, according to three sources with direct knowledge of that effort. Among the points being emphasized is that going towards impeachment proceedings could consolidate the oversight activity around President Donald Trump in addition to strengthening the party’s hand in establishing a legitimate legislative purpose to their investigative work.

A senior House aide, whose boss is in the pro-impeachment camp, said that current efforts to make this case to on-the-fence members is “hodge-podge right now.” But the aide expected it to ramp up, with potentially a single lawmaker becoming point for the operation and a formal list of targets being put together.