DISCLOSE is...

...supported by Charlie Schumer and it will...

According to The New York Times, a “reform” bill might require advocacy groups (such as NRA) “to identify all their financial donors or set up separate accounts to handle political spending and identify the donors to that account.”
Simply put: If NRA wants to use its general funds from member dues to speak out during election season, then NRA would have to give the federal government a list of every single NRA member.

The FEC database is open to whoever want to view it and with an issue as divisive as gun control who's to say someone won't use the information in the database to harass gun owners or proponents of other divisive issues. What if your boss hates the NRA and uses the database to purge any members that work for him? Under this legislation it ain't impossible. That being said the fact that Schumer wants it is enough reason to suspect and oppose it.

Sebastian has more on it.

Oh yeah, call or write your Congresscrittors or Senators to voice opposition ASAP.