In 2014, ABC, NBC, and CBS declined to carry an address by President Barack Obama on immigration.

https://www.cnn.com/2019/01/07/media/networks-trump-border-security-speech/index.html

Nancy Pelosi, Chuck Schumer demand equal airtime to respond to Trump's address
By Brian Stelter and Oliver Darcy, CNN Business
Updated 9:45 PM ET, Mon January 7, 2019

Following news that the networks would air Trump's immigration address, House Speaker Nancy Pelosi and Senate Minority Leader Chuck Schumer said in a joint statement that they should be given an equal amount of time to respond.

"Now that the television networks have decided to air the President's address, which if his past statements are any indication will be full of malice and misinformation, Democrats must immediately be given equal airtime," Pelosi and Schumer said.

The major television networks said that they will provide wall-to-wall coverage of President Donald Trump's prime time address on border security on Tuesday.

NBC, ABC, CBS, PBS and Fox broadcast network all said on Monday that they had agreed to the White House's request for air time. CNN, Fox News and MSNBC will all carry the address live, as well.
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CBS was the first of the broadcasters to say it would go ahead and carry the address. Then NBC, ABC, Fox broadcast network and PBS said the same.

There is precedent for broadcast networks declining to air a presidential speech. In 2014, ABC, NBC, and CBS declined to carry an address delivered by President Barack Obama on immigration, though Obama's White House never formally requested time after it was determined networks would be reluctant to agree to broadcast it.

Trump's Monday request for networks to air his speech touched on a number of debates that have been raging in journalism since his ascension to the Oval Office. Among them: Should his fact-free speeches be aired live? What kind of fact-checking methods should networks employ?
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