Donald Trump may be doing well in some early Republican presidential polls, but according to new research he has a lot of work to do to convince more Americans his bid for the GOP nomination is realistic.

A Gallup poll released Tuesday indicates that 74 percent of Americans don't think he's a "serious" candidate.

Interestingly, a poll by Gallup in 1999, when Trump ran on the Reform Party ticket, found an identical 74 percent of Americans didn't take his campaign seriously.

But there has been a shift in the demographics.

In 1999, only 20 percent of Republicans responded that they considered the real estate mogul a serious candidate, while in the new poll 43 percent said they did.

More trending stories

But among Democrats there was a significant drop, from 20 percent in 1999 to 12 percent now.

Gallup's polling shows 27 percent of independent voters saw his camdidacy as serious in 1999, compared to 25 percent currently.

Gallup's conclusion:

Donald Trump's candidacy has already shaped the presidential race in important ways, such as compelling other Republican candidates to address the issue of illegal immigration more forcefully. Yet even as Trump appears to be a prominent voice in the Republican race, nearly three-quarters of Americans do not take his candidacy for president seriously. The public sees his candidacy as no more credible now than in 1999, despite his decision to run for a major-party nomination this time around and his promise to spend his ample personal wealth in pursuit of his political ambitions.

You can see more details on the poll and its results on the Gallup.com website.