By Silvio Cascione

BRASILIA (Reuters) - Mexico's peso could plunge more than 10 percent to a record low against the dollar in a matter of weeks if Donald Trump wins the U.S. presidential election on Nov. 8, according to a Reuters poll of currency strategists published on Tuesday.

The likelihood of a Hillary Clinton victory is mostly priced in as opinion polls continue to show an edge to the Democratic candidate, the survey suggested.

But a small, short-lived relief rally still looks likely under that scenario following months of heated debates over Trump's proposals to build a border wall and rewrite trade agreements with Mexico.

Forecasts for most other currencies in the region were revised slightly higher compared with early October, with an amnesty program for the repatriation of illegal funds abroad helping the Brazilian real sustain some of the stronger gains this year among emerging currencies.

The median forecast of 24 strategists for the Mexican peso in a year projected the currency at 18.53 per dollar, up 2 percent from Monday's close.

However the currency will be prone to sharp swings as the U.S. election draws nearer.

Nine strategists who replied to an extra question on the peso outlook in the weeks following the election projected the currency to strengthen to 18.10 per dollar if Clinton wins or weaken to 21.50 per dollar if Trump wins, according to median forecasts.

The range of estimates was particularly broad for the "Trump wins" scenario, with one strategist forecasting the currency reaching 25 per dollar, more than 20 percent weaker than its current record low of 19.92 per dollar hit in September.

In the "Clinton wins" scenario, potential gains for the Mexican peso were seen as likely to fade quickly, as prospects of U.S. interest rate hikes and a threat of a debt rating downgrade should continue to weigh on the currency.

"We still expect the peso to come under some level of pressure into year end as attentions shift to the prospect of a Fed rate hike in December. A Clinton win would keep the door open for this," said Natalie Rivett, an economist with Informa Global Markets, in the poll.

The peso has been the second-worst performing major currency in 2016 after the British pound. It was already underperforming other emerging market currencies before Trump became the Republican presidential nominee.

"It's important to remember that the heavy depreciation of the Mexican peso started in the second half of 2014 due to fears of capital outflows as the U.S. highly accommodative monetary policy was nearing an end. This fear will persist," Banco Base economist Jesus Lopez said.