* Chinchilla support down 23 points since September
* Guevara favors switching to U.S. dollar
By Leslie Josephs
SAN JOSE, Costa Rica, Jan 19 (Reuters) - An outsider candidate from a right-wing party is gaining ground against Laura Chinchilla, favored to be elected next month as Costa Rica's first woman president, according to a recent poll.
Newcomer Otto Guevara from the fringe Libertarian Movement, has pulled into second place behind Chinchilla ahead of the Feb. 7 election, according to a nationwide survey by polling firm Unimer published in La Nacion newspaper during the weekend.
Chinchilla, a moderate from the National Liberation Party who is backed by sitting President Oscar Arias, had 40 percent of decided voters in her camp, down from 63 percent in a September poll, while Guevarra's support jumped to 30 percent from 13 percent in the earlier survey.
"Costa Rican voters are looking for an alternative to the major parties," Cathalina Garcia from Unimer told Reuters. "At this time, (Guevara) is the alternative."
Guevara's party was founded in 1994 and wants to scrap Costa Rica's currency, the colon, for the U.S. dollar, as El Salvador and Panama have done, even though the relatively stable country does not have high inflation.
Both Chinchilla and Guevara support more free trade and are tough on crime in the nation of 4 million people, which is seen as safer than its Central American neighbors and as a haven for tourists and U.S. retirees.
Chinchilla, 59, served as Arias' vice president and justice minister and is expected to continue his policies of opening up the small country to international trade and private-sector competition.
Costa Rica hopes to complete trade pacts with China and Singapore before Arias leaves office as it eyes Asian markets as a destination for its high-quality coffee beans and other agricultural products.
Arias, serving his second stint as president, pushed through a free trade deal with the United States while also forging relations with China. By law, he cannot run for reelection for another eight years and the vote likely will be the end of his career in elected office.
He won a Nobel Peace Prize for his role in helping to end the region's civil wars in the 1980s but his peacemaker reputation took a hit last year when he failed to broker a settlement to a political crisis in Honduras following a coup.
Candidates need 40 percent or more of the vote to avoid a second-round runoff in early April, now a strong possibility according to the poll, which surveyed 1,210 people and had a margin of error of 3.5 percentage points.
(Editing by Bill Trott)