In the year of 1920? This happens after say a Soviet victory at Warsaw leads to an eventual ceasefire, in which around a fifth of Poland is given to the Soviets to annex, while the rest of Poland is a Puppet state of the USSR. This leads to a border with Czechoslovakia directly with the Soviets to the East, and a border with a Soviet puppet state to the North. Now how would this affect the elections in 1925 with the Czech Communist Party? In OTL in 1925 they received 12.86% of the vote (41 Seats), second only to the 13.66% (45 Seats) gathered by the Republican Party of Agrarian and Smallholding Peoples. Now this was in OTL in which it wasn't surrounded by any Communist states directly (thought the USSR wasn't very far away.)
But how would the direct border with the Soviet Union affect the Czechs during the 1925 Election? Would it allow for the Communist party to gain a higher % of the vote? And if so could a coup occur with the help of the USSR right next door? And so we may even see an earlier Czechoslovak Socialist Republic (or something similar?) Personally I envisage that if the Communist party succeeded in this that the Soviets would demand that Carpathian Ruthenia be ceded to them (as they had in OTL just ten years later.)