White House press secretary Sean Spicer. AP Photo/Manuel Balce Ceneta The investigative-journalism site ProPublica fired back at the White House press secretary on Monday after he called it a "left-wing blog" and downplayed its report on President Donald Trump's finances.

The report, published Monday, said an unreported clause in Trump's trust document allowed the president to draw money from his 400 businesses without disclosing it.

When confronted with the report at his daily press briefing, Spicer attempted to discredit the source.

Spicer said he wasn't "aware there was any change" to the trust.

"Just because a left-wing blog makes the point of something changing doesn't mean it actually happened," he said.

The response from ProPublica was fierce. In a lengthy series of tweets, the nonprofit news site picked apart Spicer's claim and defended itself from the accusation of partisan bias.

First, ProPublica set out to prove Trump's trust document had, in fact, been changed to allow Trump to draw money from his businesses without disclosing it.

Next, it sought to prove its journalistic merit by reviving published investigative pieces that were damaging to the Trump administration.

Then it combated Spicer's "left-wing" accusation by providing examples of reports it published that were embarrassing to President Barack Obama.

All that was left was to stick the landing.