A new poll from Firehouse Strategies and 0ptimus shows that President Donald Trump’s base appears to be shrinking in swing states that were key to Trump’s victory last November.

But the president appeared to take issue with the poll, which was first reported on by Axios on Saturday, in a series of tweets Monday morning.

The Trump base is far bigger & stronger than ever before (despite some phony Fake News polling). Look at rallies in Penn, Iowa, Ohio....... — Donald J. Trump (@realDonaldTrump) August 7, 2017

The poll of 2,901 likely voters from Florida, Wisconsin, Ohio, and Pennsylvania showed a drop from 35.3 percent of voters in April who had “strongly favorable” views of Trump to 28.6 percent in August.

This drop in support is particularly high among Republicans with an almost 10 percent drop in strongly favorable views of the president among GOP likely voters. Unfavorable views of Trump among Republicans jumped from 20.5 percent to 26.9 percent in that same time.

The poll, first published on Friday, seems to have caught the eye of Trump, who tweeted Monday morning about “Fake News polling,” disputing the results.

The Trump base is far bigger & stronger than ever before (despite some phony Fake News polling). Look at rallies in Penn, Iowa, Ohio....... — Donald J. Trump (@realDonaldTrump) August 7, 2017

...and West Virginia. The fact is the Fake News Russian collusion story, record Stock Market, border security, military strength, jobs..... — Donald J. Trump (@realDonaldTrump) August 7, 2017

... Supreme Court pick, economic enthusiasm, deregulation & so much more have driven the Trump base even closer together. Will never change! — Donald J. Trump (@realDonaldTrump) August 7, 2017

Hard to believe that with 24/7 #Fake News on CNN, ABC, NBC, CBS, NYTIMES & WAPO, the Trump base is getting stronger! — Donald J. Trump (@realDonaldTrump) August 7, 2017

Firehouse Strategies, the firm behind the new polling, is made up of a number of alumni of Sen. Marco Rubio’s (R-FL) 2016 presidential campaign.