AG is right. Yes, Congress can reverse a monument designation but I don't think a President can do so by executive order. Maybe, as AG said, he might cut off funding the monument though. These monuments are all by Presidential executive order using the Antiquities Act, which was first used by Teddy Roosevelt who passed the Act to begin with. Usually the areas designated are environmentally sensitive and considered by most to be deserving of protection. Obama has set aside really big areas of the Arctic and some other places, including the Bears Ears Monument in SE Utah but he's by no means the only president to do so as they pretty much all have. https://www.washingtonpost.com/national ... story.html
For example, Jimmy Carter set aside the Misty Fjords Monument within the Tongass National Forest in Alaska and the dollars from tourism have far surpassed the value of clear cutting it.
Lengthy processes are involved in getting these monuments set up and the ones Obama established have been in the works for a long time. There's another being considered in Eastern Oregon that involves the Owyhee River and surrounding areas and involves all federal land but the local folks are up in arms as they say they are most affected and should therefore have more sayso than anybody else. Others, from the city for example, say they are just as much as citizen as the local folks and so their voice is just as weighty. Who knows? It's always very contentious.
With respect to the bill in the Natural Resource Committee that AG wanted us to write opposing, it should be understood that it is all about money and nothing to do with stewardship or management of forest lands. The bill would give each state up to two million acres of federal lands for the state to manage. Currently Alaska is going bankrupt because of low oil prices and their oil fields are drying up and so Rep Don Young's bill is about jobs cutting timber. It's not about whether the state or the feds can better manage forests. I lived in the Tongass for sixteen years and I know the forestry politics there pretty well. I saw the state clear-cut old growth forests up to our town's city limits and right down to our public beaches, and which ruined red salmon runs in vast watersheds and then the state sent the timber "in the round" to Korea. The only jobs we got were for cutting these gorgeous trees down; Korea got the jobs for making it all into plywood while our town's veneer plant stood idle next to the landing where Korean ships were loaded! See image I took below and our veneer plant in the distance.
So this bill (H.R 3650) is a land grab. Nothing more. You saw where it passed the Natural Resources Committee because of near complete Republican support. Were it to have come to a vote in the House it would have been defeated, and were it to have somehow passed both houses and gone for Obama's signature he would have vetoed it because he's pretty level headed when it comes to looking after our environment. Next month, with Republicans controlling both house and senate (and Trump in the oval office) many fear this bill could become a reality. Hopefully there are more Republicans than Zinke with an environmental conscience.
Personally, I'm for a balance in environmental issues that pit preservation against development. I am not all about preserving just for the sake of preserving but hopefully we will have thousands of years to screw up the planet so I don't feel compelled to do it all in our generation. And with the population of the earth having doubled since 1960 I expect they'll be lots of issues ahead.