House Speaker John Boehner hit the pause button Thursday on comprehensive immigration reform — just a week after his party unveiled its priorities for any such overhaul. Boehner has said for the past year that he wants to pass an immigration bill, even though he wouldn't bring the bill the Senate passed last year to a vote in the House. Why the new halt? There are three key reasons, NBC News reports. For one, there's a real fear among the House GOP that moving immigration reform now could divide the party in a mid-term election year. Also, Boehner has cited a lack of "trust" between the House GOP and President Barack Obama — with Republicans worrying Obama would undermine their bill with executive actions. And finally, Republicans have yet to figure out what their emphasis on "border security" would practically mean.