( CNN ) -- As Sen. John McCain prepares to promote free trade during a high-profile trip to Colombia and Mexico , a poll out Tuesday suggests the issue may be a political hurdle as the general election campaign heats up . Sen. John McCain 's free trade stance could pose a problem in November , according to a new poll . According to the CNN/Opinion Research Corporation poll , 51 percent of Americans view foreign trade as a threat to the economy -- the first time in a CNN poll that a majority of Americans report holding negative views on free trade . That compares with only 35 percent of Americans who felt free trade posed a threat to the economy in 2000 , and 48 percent who felt it was a threat in 2006 . Now , only four in 10 Americans say free trade presents an opportunity for economic growth , a sentiment that clearly makes the issue a challenge for McCain , especially in the crucial Rust Belt states most affected by the loss of manufacturing jobs over the last decade . `` It 's possible that John McCain 's decision to highlight his free trade position may wind up losing him some votes among Americans who feel threatened economically by competition from other countries , '' CNN polling director Keating Holland said . `` Recent polls in states like Pennsylvania and Michigan have shown McCain well behind Barack Obama . Calling attention to his stand on an issue like trade may be a part of the problems he apparently faces in those Midwestern states . '' The poll also shows that some of the key voting blocs McCain is courting are most against free trade . Women , older Americans and lower-income voters report feeling the biggest threat from unfettered trade . Many of these voters were particularly receptive to Sen. Hillary Clinton in key states during the Democratic primary as she increasingly developed an anti-trade stance . The survey results come as McCain , who is a strong supporter of the North American Free Trade Agreement , heads to Colombia and Mexico to promote the advantages off a free trade policy and economic cooperation . He made a similar trip to Canada earlier this month . Campaigning Monday through Pennsylvania -- one of the crucial political battleground states most affected by the loss of manufacturing jobs -- the presumptive Republican presidential nominee acknowledged many voters disagree with him on the issue . `` I understand it 's very tough . But for me to give up my advocacy of free trade would be a betrayal of trust , '' he told reporters Tuesday . `` And the most precious commodity I have with the American people is that they trust me . '' In another challenge for McCain , the new CNN survey indicates Americans continue to rank the economy as the most important issue in deciding their vote for president . Nearly six in 10 voters say the country 's poor economic conditions will be extremely important -- ranking the economy as the No . 1 issue in this campaign out of 15 issues tested in the poll . That finding represents a clear change from the beginning of this year , when the war in Iraq and the economy were tied as the top campaign issues . Now , the economy is eight points ahead of Iraq -- a fact that could pose a threat to McCain , who has admitted he is more comfortable discussing foreign policy issues than economic ones . Rising gas prices are also among voters ' concerns , with nearly 50 percent saying the issue will play an important role in their vote for president . That number is just behind those that say the economy and Iraq are important , a clear sign that higher prices for gasoline are the primary reason for voters ' economic worries , though not the only one . `` It also means that a significant number of voters are concerned about other economic woes , like the stock market or unemployment , rather than gas prices , '' Holland said . `` Unless there is a noticeable upturn in the country 's economy between now and November , this election is likely to be dominated by economic concerns . '' The poll , conducted June 26-29 , surveyed 906 registered voters and carries a margin of error of plus or minus 3.5 percentage points .
New CNN/Opinion Research Corp . Poll released Tuesday . It suggests the free trade issue may pose a problem for McCain . Poll : 51 percent of Americans view foreign trade as a threat to the economy .