Transcript for President Trump tweets support of FEMA's efforts during Hurricane Harvey

Harvey, this is the first natural disaster on Donald Trump's watch as president. He was briefed on the storm yesterday and signed a disaster declaration for the state of Texas. As we know, moments like this can be defining moments for a presidency and ABC's Mary Bruce joins us from the white house with more on the white house's response. Reporter: Good morning, well, the president is up and tweeting and taking this storm very seriously. Urging everyone to stay safe. Just a few moments ago he was cheering on his FEMA administrator tweeting out a picture of a FEMA briefing saying you're doing a great job, the world is watching. Be safe. And the world is watching, of course, not just this hurricane but also how this president responds. This is a big test for president trump. The first natural disaster on his watch and even Republicans senators like chuck grassley were out urging him to not repeat mistakes of the past referencing president bush's response to hurricane Katrina widely criticized for being too slow of a response. The president is also up tweeting responding to chuck grassley saying he got his message loud and clear. The president says we have fantastic people on the ground who got there long before the hurricane, so far so good says president trump. He is now at camp David and will be receiving updates throughout the day and have a teleconference with his FEMA administrator and homeland security team later this morning. But, Mary, even as this storm was making landfall overnight, president trump was making news on a number of fronts, some of them extremely controversial. Can you walk us through what happened. Reporter: Extremely controversy last 24 hours for this presidency, Dan. The president overnight anewsing that he is pardoning sheriff Joe arpaio, the former Arizona sheriff who has become a lightning rod in the debate over immigration in this country. Now, of course, arpaio was convicted of criminal contempt for ignoring a judge's order not to detain suspected undocumented immigrants, now, the president did not mention that conviction when he announced this pardon which was somewhat expected but the president did say and praised arpaio saying he was a worthy candidate for a presidential pardon. Of course, many of the president's critics strongly disagree. Some critics are calling this presidential endorsement in effect of prejudice. ABC's Mary Bruce at the white house. Mary, thank you.

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