* Markets expect key interest rate to stay on hold at 4.25%

* Weaker rouble, geopolitical risks limit room for rate cuts

* Bank of Russia to deliver decision at 1030 GMT on Friday

* Governor Elvira Nabiullina to present decision at 1200 GMT

* reuters://realtime/verb=Open/url=cpurl://apps.cp./Apps/cb-polls?RIC=RUCBIR%3DECI poll data

MOSCOW, Oct 19 (Reuters) - Russia's central bank is likely to keep its main interest rate on hold on Friday ahead of the U.S. presidential election and following a slide in the rouble on concerns over geopolitical developments, a Reuters poll showed on Monday.

Twenty-five of the 29 analysts and economists polled said the central bank would keep its key rate at 4.25%, keeping the cost of lending unchanged since July.

"We think that the regulator's main focus will be on a range of risks related to rising volatility on financial markets and the upcoming political events in the United States," said Rosbank, a Russian unit of Societe Generale.

Volatility in Russian assets has risen following turmoil in neighbouring Belarus, the suspected poisoning of Kremlin critic Alexei Navalny and conflict in the South Caucasus.

"Geopolitical risks remain uncomfortably elevated," Citi said. The risk premium remains "at levels that may be too high for the CBR to plunge into a rate cut, and in particular so in the run-up to the US presidential elections" on Nov. 3, it said.

Central Bank Deputy Governor Alexei Zabotkin reinforced expectations for no rate change by saying last week that the bank would consider the same factors as in September when it meets on Oct. 23, analysts said.

The central bank started cutting rates early this year when the economy took a hit from a plunge in prices for oil, Russia's main export, and from the coronavirus pandemic and subsequent lockdowns that hit business activity.

Four analysts predicted the central bank would continue cutting rates to support the economy given that inflation is still below its 4% target.

VTB Capital said other countries including Mexico, Columbia, Egypt and Vietnam had cut rates in the past month so Russia could consider following suit given that inflationary pressure remains low.

Zabotkin's comments last week that the central bank will focus on downside inflation risks in the medium term "reveal the CBR's logic that would allow it to cut the policy rate by 25 bps in the next rate-setting meeting," Credit Suisse said.

The rate decision is due at 1030 GMT and will be followed by an online media conference with Governor Elvira Nabiullina. (Writing by Andrey Ostroukh; Editing by Hugh Lawson)