* Soybeans add on export optimism, slower harvest

* Wheat waits as U.S. weather looks to improve

CHICAGO, Nov 3 (Reuters) - Chicago soybean futures climbed on Tuesday on export optimism and a slower-than-expected U.S. harvest pace, traders said.

Wheat firmed as traders monitored dryness in U.S. and Russian growing belts, while corn traded higher on continued hopes of China buying.

The most-active soybean contract on the Chicago Board of Trade (CBOT) was up 13-3/4 cents to $10.66 a bushel as of 11:42 a.m. (1742 GMT), the contract's biggest single-day gain since Oct. 9.

CBOT wheat was up 1-3/4 cents to $6.09-1/4 a bushel while CBOT corn added 3 cents to $4.00-1/2 a bushel.

Soybeans climbed on news that Brazil, the world's biggest soy exporter, is buying U.S. soybeans as the country grapples with rising prices of domestic food staples.

Analysts say corn, rice, wheat and cotton exports to Brazil are possible from the United States, and more likely than soybean sales.

"It's going to be difficult, with the GMO (soybean) varieties that are locked out of Brazil, to be able to re-export," said Mike Zuzolo, president of Global Commodity Analytics. "Everything they take is going to have to be for domestic consumption."

Both corn and soybean futures were supported by lower-than-expected harvest progress numbers reported by the U.S. Department of Agriculture on Monday. The U.S. harvest was 82% complete for corn and 87% complete for soybeans, ahead of the crops' respective five-year averages, but both fell short of average analyst expectations.

Meanwhile, U.S. voters headed to the polls in many battleground farm states to cast ballots for either President Donald Trump or Democratic rival Joe Biden.

Some analysts say the recent spate of grain buying from top importer China will not be impacted by the election's outcome.

"No matter who’s president, China still needs to feed their hog herd," said Dan Smith, senior risk manager at Top Third Ag Marketing.

(Reporting by Christopher Walljasper; Additional reporting by Gus Trompiz in Paris and Naveen Thukral in SIngapore)