Douglas Letter, the top lawyer for the U.S. House of Representatives, effectively got a dress rehearsal Friday for next week’s arguments in the House’s quest to block President Donald Trump’s transfer of money to fund construction of the border wall that was signature of the president’s 2016 election campaign.

The Democratic-led House of Representatives filed suit against the Trump administration in U.S. District Court for the District of Columbia last month claiming that the president’s declaration of a national emergency at the nation’s southern border didn’t justify funneling away funds appropriated to pay for anti-narcotics projects and military construction. Letter is set to argue the House’s motion for a preliminary injunction next Thursday before Judge Trevor McFadden of the U.S. District Court for the District of Columbia.