It means the billionaire will only run as a Republican candidate, after the Party officials forced him to show his full support to the Republicans.
The latest polls extends Trump's lead to 30%.
Our correspondent Nick Harper was at the event in New York where Trump made the announcement and says unless Trump breaks his promise he can only run as a Republican.
IN: "That effectively means..."
OUT: "...nominee."
DUR: 30 seconds
CLIP 1: http://www.fsnradionews.com/feeds/0903trump-nh1.mp3
Our correspondent Nick Harper was at the event in New York and says it was tactical move by the Republican Party.
IN: "It's something..."
OUT: "...votes."
DUR: 29 seconds
CLIP 2: http://www.fsnradionews.com/feeds/0903trump-nh2.mp3
[ALT] At an event in New York, Trump confirmed he was now fully behind the Republican Party.
IN: "I have signed..."
OUT: "...we will win.
DUR: 20 seconds
CLIP 3: http://www.fsnradionews.com/
Trump is now leading the polls with 30% - something he said was never expected.
IN: "I was always..."
OUT: "...
DUR: 21 seconds
CLIP 4: http://www.fsnradionews.com/
Speaking about one-time Republican front-runner Jeb Bush, Trump said he didn't have the energy to run the country.
IN: "I watched him..."
OUT: "...lobbyists."
DUR: 20 seconds
CLIP 5: http://www.fsnradionews.com/
Following Kanye West's announcement he wants to run for President in 2020, Trump said he supported the music star's plans.
IN: "Kanye West..."
OUT: "...that back."
DUR: 15 seconds
CLIP 6: http://www.fsnradionews.com/