His organization keeps a scorecard for each Washington legislator on gun issues, and spends millions on campaign contributions to favored candidates.
In Congress, some influential Democrats join virtually all Republicans in opposing, or at least questioning, a renewed ban on semi-automatic weapons like the Bushmaster AR-15-style rifle used in the Newtown shootings.
Senate Majority Leader Harry Reid, who gets high marks from the NRA for his opposition to past gun control efforts, has indicated support for expanding background checks but refuses to endorse a new weapons ban.
According to Reid, a bill from the Judiciary Committee was unlikely to include an updated weapons ban, but he would allow a vote on the provision during floor debate.
Such a vote would amount to Feinstein's last stand on the issue.