Washington, DC (LifeNews.com) -- A new poll shows that an overwhelming majority of Republican voters are still strongly pro-life on the issue of abortion and see it as a reason for being a member of the party. The poll also found a sizable number of Republicans who say they would not likely vote for a pro-abortion Republican candidate.

The Republican-leaning Fabrizio-Mclaughlin polling firm surveyed 2000 self-identified GOP voters nationwide from May 28 to June 3.

The poll found that GOP voters are becoming more conservative with those using that label to identify themselves moving up to 71 percent form 55 percent. Moderates dropped 10 percent to 21 percent of all GOPers and liberal Republicans make up only four percent of the party.

When it comes to their views directly on the issue, the survey found 28 percent of Republicans say abortion should be illegal under any circumstances. Only 16 percent of GOP voters say abortion should always be legal.

Another 52 percent of Republican voters say abortion should only be allowed in "certain circumstances," although the poll didn't say what situations are included in the vague question.

Typically a sizable portion of those in the middle category favor keeping abortions legal in cases of rape or incest or to save the life of the mother -- which constitute less than two percent of all abortions, according to the pro-abortion Alan Guttmacher Institute.

As a result, about 80 percent of Republican voters want all abortions to be illegal or abortions to be legal in a rare handful of cases.

Another question in the poll asked the GOP voters to identify themselves as "pro-life" or "pro-choice," and 61 percent of Republicans say they are pro-life while just 34 percent said they're not.

The poll also found that a large block of 35 percent of Republicans would be unlikely to vote for a presidential candidate who agreed with them on other issues but disagreed with them on abortion.

The result is very significant for former New York mayor Rudy Giuliani, who is the top pro-abortion candidate seeking the GOP nod.

The survey shows that more than one-third of Republican voters won't consider him for president, which severely limits his ability to capture the nomination. Should he win the nod for the general election, the poll makes it appear he could have difficulty winning because he would lose such a substantial part of the Republican base.

When looking at why members of the party are Republicans, the abortion issue plays a strong role.

Some 7 percent of Republicans say they are members of the GOP specifically because of its pro-life stance on abortion.

But another 26 percent cite the party's conservative views, 22 percent say they have similar beliefs as the party, 13 percent cite moral or religious issues, and 19 percent said they were raised Republican or favor candidates of the party.

While not directly related to abortion, pro-life views play a role in each of the categories.

When asked what issue best defines the Republican Party, abortion came in third with 8 percent saying it primarily separates the GOP from the Democratic Party. Another 11 percent cited family values or moral issues, which can include abortion.