U.S. Republican presidential candidate Donald Trump takes the stage at Ladd-Peebles Stadium Aug. 21, 2015, in Mobile, Alabama. The latest polls indicate his favorability rating is improving. Getty Images/Mark Wallheiser

WASHINGTON -- For months there has appeared to be one roadblock standing between Donald Trump and victory in the Republican presidential primary campaign: The large number of people who didn’t like him. While poll after poll found him in the lead, they also found him with some of the highest unfavorable numbers -- meaning people had already formed an opinion of him, and it wasn’t positive.

But two polls released Tuesday in early primary states show that dislike evaporating. A South Carolina poll conducted by Monmouth University found Trump with 58 percent holding a favorable opinion and 28 percent, an unfavorable opinion. A Public Policy Polling survey of New Hampshire voters found 56 percent holding a favorable opinion and 32 percent, an unfavorable opinion.

“It’s a phenomenon we have never really seen before -- an already extremely well-known figure who can completely flip his favorability ratings in the span of weeks [without the intervention of a national emergency or similar event],” said Patrick Murray, the pollster who conducted the South Carolina poll and has also recently conducted surveys nationally and in Iowa. “But of course, that rule has applied to our experience with typical politicians. Trump is completely outside the box.”

Donald Trump
Republican presidential candidate Donald Trump pledged to give greater power to police officers to "get rid" of gangs. Pictured: Trump speaks during a rally at Ladd-Peebles Stadium in Mobile, Alabama, Aug. 21, 2015. Mark Wallheiser/Getty Images

Trump's rising popularity counters the conventional wisdom that his high negatives would make it impossible for him to be the Republican nominee. Political observers have repeatedly declared his campaign's boom was about to go bust: After he said many Mexican immigrants were rapists; after he opined that John McCain wasn't a war hero; after he complained (and made possibly sexist remarks) about Fox News' Megyn Kelly. The expectation was voters would tire of the reality TV star and his support would begin to shrink.

Instead, Trump has only seen public opinion of him among Republican primary voters improve.

Monmouth conducted a national poll earlier this month that found Trump with a favorability of 52 percent -- up from 40 percent three weeks earlier. And notably, his unfavorable rating dropped from 41 percent to 35 percent.

This far from Election Day, favorability numbers may be more important than horse race, match-up polls. Trump has been holding leads in double digits, but also had pluralities or majorities who saw him in a negative light.

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Conventional wisdom has always held candidates can move people who hold no opinion of them. But getting those who already have an opinion to change their minds is a lot more difficult.

Just how far has Trump come in a place like South Carolina? In April, a Winthrop University poll of the state’s Republicans found 74.2 percent of respondents said they would not consider voting for him. Now a majority of those polled have a positive view of the real estate mogul.

In New Hampshire, the trend has also been stark. PPP conducted an April poll in the Granite State that found 41 percent with an unfavorable opinion of Trump and 40 percent with a favorable opinion.

“This is by far the best we’ve found Donald Trump doing anywhere during his entire surge,” said Dean Debnam, president of Public Policy Polling. “If anything he just seems to be getting stronger as the campaign rolls on.”