The Russians wished to cast doubt on the legitimacy of ANY US President, and in this they have been relatively successful.
The Russians may have interfered in local elections in both Los Angeles and New York City to produce overwhelming majorities for Herself, giving her a large part of the majority in the popular vote in California and New York State, much of the rest coming from locally generated vote fraud. So on paper, while it looked like Herself got the majority of votes, those supernumerary votes were very unevenly distributed, thus Trump won on the electoral college vote by a sizable margin. The “popular vote” count threw doubt in the accuracy of the measure of the temper of the people across the nation, and it was enough to keep things in ferment several years after the fact.
I sincerely believe the Russians, as well as other foreign entities, conspired to skew the final popular vote tally in not only the Presidential election, but in many House and Senate races as well. Those marginal races that went to Democrats in the 2018 election? Clandestine Russian money and influence, as well as the usual voter fraud in those districts.
So.... if you are the Russian government and you want to destroy the US, you just put Democrats in all the offices.