Cruz has been doing the NRA's bidding, and it's coming back to haunt him.

Texas Democratic Rep. Beto O’Rourke is crushing his opponent, Republican Sen. Ted Cruz in fundraising.

In the most recent federal filings, Cruz pulled in $800,000 while O’Rourke nearly tripled that with a $2.3 million haul.

But beyond the top line numbers, there is more trouble for Cruz: He has spent $1.2 million, far above the amount he raised.

“The grassroots momentum of our people-powered campaign has shown its full force across the state in the first 45 days of 2018, and it will continue to do so as Texans prove they’re more than a match for the PACs and special interests,” O’Rourke declared in a statement on his campaign’s success.

The response from Cruz’s campaign has been notably different: “This is serious.”

In 2012, Cruz easily won his election by 16 percent, even as Democrats won nationally under President Barack Obama.

But with polls showing O’Rourke within single digits of him, and Cruz attaching himself to the unpopular Trump, the race has been rated only “likely” Republican instead of a “solid” seat.

That change is surely due in part to Cruz’s recent outrageous comments on guns, echoing his NRA supporters.

He bragged to the conservative CPAC conference about stopping gun reform after the Sandy Hook massacre. He explained that he “happily led the fight” against a bill to expand background checks to gun show and internet sales, even though most Americans support it.

After the murders at Stoneman Douglas High in Florida, Cruz actually laughed at the idea of doing anything about school violence.

Texas voters see Cruz praising and hailing Trump, bragging about enabling mass shootings, and doing the NRA’s bidding. And they are joining the blue wave of voters in rebuking the GOP from coast to coast.

Cruz’s campaign got one thing right. This is “serious.”