Trump is solidly against illegal immigration and excessive legal immigration, an issue that represents an existential threat the the United States. Moreover, Trump is a fighter and has a record of accomplishing large projects, traits that distinguish him from many conservatives in Washington.
As was Romney.2012.
and excessive legal immigration,
Granted, I don't recall Romney.2012 taking a position on that. I do recall this: 'Romney's solution of "self deportation" for illegal aliens made no sense and suggested that Republicans do not care about Hispanics in general, Trump says [in an interview with Newsmax]. "He had a crazy policy of self deportation which was maniacal," Trump says.' - http://www.freerepublic.com/focus/news/3310076/posts
Trump is a fighter and has a record of accomplishing large projects
Which doesn't necessarily make him a conservative, much less more conservative than Romney.2012.