PHOENIX — Donald Trump was just a few weeks into his candidacy in 2015 when he came to Phoenix for a speech that ended up being a bigger moment in his campaign than most people realized at the time. Trump savaged his critics and the media, vowed to fine Mexico $100,000 for each immigrant entering the country illegally, talked tough on trade, promised to return America to its winning ways and borrowed a line from Richard Nixon in declaring, “The silent majority is back.” The packed crowd ate it up — the raucous enthusiasm an early sign of the overwhelming support among Trump’s base that would help carry him to the presidency. As Trump returns to Arizona on Tuesday in need of another big moment, he will find a place where his agenda and unconventional leadership style have consumed the political landscape and elevated the state’s status in the national fight for control of power in Washington in 2018. It was Arizona senator John McCain who cast the vote that derailed Trump’s effort to repeal the health care law.