KYIV, Ukraine — Washington may be obsessed with the impeachment inquiry over President Trump’s dealings with Ukraine, but it was far from the minds of a few thousand protesters who gathered on a recent frosty night in Kyiv to vent their anger at their own country’s president, Volodymyr Zelensky, over his peace overtures to Russia.

If he struggled to resist demands by Mr. Trump for investigations affecting next year’s United States elections, some protesters said, imagine what will happen when he meets President Vladimir V. Putin on Monday for talks on ending the war in eastern Ukraine. As speakers derided Mr. Zelensky as soft on Russia, the crowd answered with cries of “No to capitulation!” and “Treason!”

Mr. Zelensky campaigned for the presidency on a two-plank platform of fighting corruption and ending a grinding war with Russian-backed separatists in eastern Ukraine that has killed at least 13,000 people.

While the peace effort has received less notice, it is undoubtedly the more politically treacherous of the two undertakings. Everyone is against corruption, in theory at least, but there are sharp divides over how to deal with Russia, which is widely despised by Ukrainians outside the breakaway eastern territories.