LOUISVILLE, KY - MAY 20: Republican presidential candidate Donald Trump is introduced with Chris Cox (L), Executive Director of the NRA Institute for Legislative Action and Wayne LaPierre (R), Executive Vice President of the National Rifle Association, at the National Rifle Association's NRA-ILA Leadership Forum during the NRA Convention at the Kentucky Exposition Center on May 20, 2016 in Louisville, Kentucky. The NRA announced their endorsement of Trump at the convention. The convention runs May 22. (Photo by Scott Olson/Getty Images)

Any doubts about whether the NRA is feeling the pressure of an increasingly powerful gun violence prevention movement can be quelled by reading Wayne LaPierre's latest keynote rant. While never the most coherent thinker, this year's stream-of-warped-consciousness epic hate poem, showed LaPierre giving up all pretense and appealing directly to his audience's worst fears, deepest prejudices and festering anger. Here's why:

For years the National Rifle Association has maintained its stranglehold on national politics by convincing politicians that it is politically invincible. But now there is fresh evidence -- actual numbers -- that show the NRA is increasingly feeling the heat of Americans' shifting attitudes about gun violence prevention. This is a big deal.

The numbers appear in a tax form known as a 990, which charitable organizations must file every year to let the Internal Revenue Service know what they are up to. The NRA's 990 for the year 2014 just appeared online at Guidestar, where all such filings are made public.

The invincibility myth has always been just that -- a myth -- the apocryphal story of a massive army of passionate gun lovers who will exact revenge on any who dare to cross them. The truth is far more complicated. As we show in our latest film, Making a Killing: Guns, Greed, and the NRA, the NRA's resources come largely from the gun industry and the organization's actual membership does not actually agree with all their stances.

Nonetheless, too many politicians believe the NRA can't be beat and so are unwilling to step up and try. The result is the kind of tragedies we chronicle in Making a Killing -- suicides that could have been prevented, children unintentionally shooting other children, women living in fear of armed, dangerous domestic abusers. The tragedies continue.

Those politicians should take a look at the NRA's latest 990s and reconsider their stances - or perhaps, rediscover their backbones.

The major takeaway is that the NRA in 2014 lost money -- that is, they spent more than they took in. Overall, the gun manufacturers' sales and marketing team -- our shorthand for the real NRA -- grossed $37 million less in revenue than in 2013.

A hefty chunk of that decrease is in members due. Much of the myth of the NRA's power stems from its constant refrain of the number 5 million -- as in, "we have 5 million members willing and eager to do our bidding at any time." That figure has always been suspect, with numerous investigations uncovering schemes to inflate the rolls.

Now the latest 990 offers more proof that the numbers are smaller than advertised and getting smaller still. In 2014 member dues plummeted by $47 million -- from $175 million to $128 million, according to the NRA's filing.

Other telling and related facts include:

• Spending more to keep politicians in line: The NRA's Institute for Legislative Action -- a.k.a. lobbying arm -- spent $47 million in 2014. That's considerably more than the $27 million they spent in 2013 lobbying to defeat a bill that would have expanded criminal background checks for private gun sales, which gained traction in the wake of the Sandy Hook massacre. This spending surge suggests the NRA's concern about lawmakers willingness to march in lockstep going forward.

• Spending more to polish their image: The NRA's public relations agency Oklahoma raked it in, with $16.9 million in billing in 2014 -- compared to $14.5 million in 2013 -- the year after Sandy Hook. That's hardly a show of strength.

None of this means that the NRA is not still a formidable foe. The gun industry is worth billions of dollars and they will continue to spend what is necessary to keep America frightened, angry and armed. For politicians though, it should be a wake up call: Next time you are faced with an opportunity to do what is clearly right -- expanding background checks and keeping terrorists from owning guns, just for starters -- think about these numbers. If you are not worried enough about the safety of the people you are charged with representing, perhaps the increasing vulnerability of the NRA will convince you to worry about the safety of your own political life.