WASHINGTON — Attorney General Jeff Sessions’ decision to reopen the door to more federal enforcement of marijuana laws has created a growing backlash within his own party, and potentially an election-year problem for some of its most vulnerable members.

Sen. Cory Gardner, R-Colo., who has announced plans to block all Justice Department nominees unless Sessions backs down, met with the attorney general on Wednesday but said the two are no closer to agreement beyond a pledge to “continue our discussions and conversations, and perhaps even expanding those conversations to others who are in Congress.”

Meanwhile, Gardner said he is marshaling fellow lawmakers to oppose the new policy. A dozen senators met Tuesday in Gardner’s office “to talk about what we need to be doing legislatively and the direction we should be pursuing in Congress on this matter,” he said.