MOSCOW — Months before a whistle-blower’s complaint came to light this week, raising alarms over dealings between the Trump administration and Ukraine, the issue was roiling politics in Kiev.

The whistle-blower’s specific allegations remain cloaked in mystery, but they involve at least one instance of President Trump making an unspecified commitment to a foreign leader along with other actions, according to news reports in Washington. At least part of the allegation deals with Ukraine, the reports say.

But for months now in Kiev, the Ukrainian capital, the government of the neophyte president, Volodymyr Zelensky, has been grappling with unwelcome political pressure by associates of Mr. Trump. Rudolph W. Giuliani, Mr. Trump’s personal lawyer, said in an interview Thursday night on CNN that he had pressed Ukrainian officials to pursue investigations into Mr. Trump’s political opponents, including former Vice President Joseph R. Biden Jr. and his family.

Mr. Zelensky took office in May, but even before then, Mr. Giuliani has said he sought a meeting with the president to investigate a natural gas company, Burisma, where Mr. Biden’s son, Hunter Biden, had served on the board of directors.