Denver Mayor Mike Johnston is heading to Washington, D.C., as the head of a coalition of mayors asking for help with the migrant crisis.

Johnston, a Democrat, will use the United States Mayors Conference to advocate federal assistance in dealing with the migrant crisis. Denver is one of several Democratic-controlled cities that have been the target of Gov. Greg Abbott’s (R-TX) migrant busing campaign, which has seen Texas ship thousands of immigrants to the sanctuary cities.