Urban would bring Capitol Hill connections, but no prior White House experience.
Spicer pushed back against allegations, but did not deny, that President Trump's son-in-law and Senior Advisor Jared Kushner tried to set up back channel communications with Russian Federation for private communication. The White House said Dubke will remain in the post until a successor is in place.
Michael Dubke's departure comes as Trump considers major staff overhaul to counter allegations of collusion with Russian Federation.
The White House on Wednesday took its first public steps to cordon off response efforts to the Russian Federation probe from the day-to-day work of the administration, acknowledging openly that President Donald Trump had hired an outside attorney to handle the swirling controversy. Moscow has denied US intelligence agencies' conclusion that it meddled in the campaign to try to tilt the election in Trump's favor.
Dubke resigned just before Trump left on his foreign trip but will stay on until a transition is concluded, Reince Priebus, the White House chief of staff, said.
Numerous reports said the president was losing patience with Spicer, Chief of Staff Reince Priebus, top strategist Steve Bannon and even son-in-law Jared Kushner, who is also involved in the Russian Federation probe.
"Mike will assist with the transition and be a strong advocate for the president and the president's policies moving forward", he said.
Dubke joined the administration in February. Dubke founded Crossroads Media, a GOP firm that specializes in political advertising.More news: Samsung has a 6GB Galaxy S8+ to boost sales in India
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Dubke, 47, had been a behind-the-scenes player who helped manage the White House communications strategy, including the aftermath of President Trump's firing of FBI Director James Comey.
It's unclear whether other staff moves are imminent.
If an overhaul is in the works, White House officials aren't letting on.
Senior adviser to President Donald Trump Kellyanne Conway told "Fox and Friends" Tuesday that son-in-law Jared Kushner had every right and responsibility to set up a secret backchannel with Russian Federation.
"I think when you see instances like that get perpetrated over and over again, that is frustrating", Spicer later said of the tweet. He later added: "It's an ongoing conversation, and that's a fair way to put it".
Reports continue to circle about other impending White House staff changes, and the briefing followed news Tuesday morning that communications director Michael Dubke had resigned.
Spicer also fielded questions about a White House shake up.
The latest revelations to emerge last week involved Trump's son-in-law and top aide, Jared Kushner.
The Senate Intelligence Committee notified the White House in March that it planned to question Kushner about the meeting.