* Fernandez has huge lead over opposition challengers
* Socialist Binner moves into distant second place
BUENOS AIRES, Sept 14 (Reuters) - Argentine President Cristina Fernandez has a massive lead over a splintered field of opponents less than six weeks from a presidential election, a poll showed on Wednesday.
Fernandez's support now stands at 51.9 percent, more than 40 points ahead of her nearest rival -- Socialist provincial governor Hermes Binner, the survey by local pollsters Management & Fit showed.
Center-leftist Fernandez won just over 50 percent of votes in an August primary, which was seen as a dress rehearsal for the Oct. 23 election because all political parties had already anointed their candidates and voters could choose among them. [ID:nN1E77E00L]
Binner has voter support of 11.6 percent, Wednesday's poll showed. That marked an increase of 1 point on his performance in the primaries and put him ahead of Ricardo Alfonsin, a social democratic legislator who had been running second.
Alfonsin trailed third with 7.5 percent, down from the 12 percent he polled in the August primary.
Management & Fit's survey showed San Luis provincial governor Alberto Rodriguez Saa in fourth place on 6.0 percent.
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Fernandez, a center-left Peronist who chose Economy Minister Amado Boudou as her vice presidential candidate, vows to continue current policies that include a strong state hand in the economy, hefty energy and transportation subsidies and trade protectionism.
She is enjoying approval ratings of close to 60 percent thanks to brisk economic growth, the opposition's failure to mount a convincing challenge and lingering public sympathy following the death last year of her husband and predecessor as president, Nestor Kirchner.
Under Argentine election law, candidates are guaranteed a first-round victory if they win more than 45 percent of votes or at least 40 percent with a 10-point advantage over the next biggest vote-getter.
The Management & Fit poll was taken between Sept. 2 and Sept. 6 among 2,031 people. The margin of error is plus or minus 3.1 percentage points. (Reporting by Alejandro Lifschitz; Writing by Helen Popper) (firstname.lastname@example.org; +54 11 4510 2505; Reuters Messaging: email@example.com))