The struggle for power in Haiti after the assassination of the country’s president has spilled onto K Street, where rival Haitian politicians, business leaders and interest groups are turning to lobbyists to wage an expensive and escalating proxy battle for influence with the United States.

Documents, interviews and communications among Haitian politicians and officials show a scramble across a wide spectrum of interests to hire lobbyists and consultants in Washington and use those already on their payrolls.

A group text chat in the days after the killing of President Jovenel Moïse that included Haitian officials, political figures and American lobbyists showed them strategizing about countering American critics and potential rivals for the presidency and looking for ways to cast blame for the killing, according to copies of the messages obtained by The New York Times and confirmed by some of the participants. The chat began before the assassination and originally included Mr. Moïse, though it appeared to take on a more frenetic tone after he was gunned down in his home this month.

The texts and other documents help bring to life how lobbyists from firms including Mercury Public Affairs — which was paid at least $285,000 in the second half of last year by the Haitian government — are working with allied politicians to position successors in the wake of the assassination. In addition to Mercury, lobbying filings show that Haiti’s government is paying a total of $67,000 a month to three other lobbyists or their firms.

At the same time, competing political factions are looking for ways to develop backing in Washington for their own candidates.