The Politico.com Energy Report website says, "Top Democrat appropriator Norm Dicks thinks his party has a “decent shot” to vote down an Interior-EPA spending bill rider that would prevent the Obama administration from blocking new uranium mining on public lands surrounding the Grand Canyon." The rider was introduced by Rep. Jeff Flake.
Meanwhile, in an opinion piece ("GOP lawmakers have Canyon under siege") yesterday in the Arizona Republic, Congressman Raul Grijalva raised the specter of mining taking place in the Canyon itself, saying "Arizona doesn't want to open the Grand Canyon for mining, drilling or any other kind of disruption. The Canyon isn't just a pile of rocks or a vein of minerals waiting to be turned into cash."
The million acres of federal lands under debate are actually BLM and Forest Service lands [right, credit, BLM] outside the national park boundaries, but there is widespread public perception that mining is proposed inside the park and inside Grand Canyon.
update 8pm: Keiran Suckling, Executive Director of the Center for Biological Diversity, warns in an op-ed posted this evening, that if the House Appropriations rider passes, "The place that millions consider a national treasure could become a radioactive industrial zone."
note: for some unexplained reason, the last half of this post was not showing up when it was posted online. The only way I can get it to appear is to disable the live links to the sources. First time I've had this happen.