"Voting democrat is the same as not voting at all and that there is no precedent for not voting".
“Years and years ago it may have been an acceptable tactic to organize a people’s ticket of solid worker and revolutionary credentials and arm it with an ideal platform—only to be defeated by a mud-slinging opportunist-warlord, demonstrably inferior, scum-willing pig. Then pass out a pamphlet to explain to the people how the system has failed them, or speak it in Pershing Square—or, years ago, in the Campus Hall. Today it is not a tactic—it’s counterrevolution[…] The effect has been reformism rather than revolution. When any election is held it will fortify rather than destroy the credibility of the power brokers. When we participate in this election to win, instead of disrupt, we’re lending to its credibility and destroying our own. With all the factors of control over the electoral process in the hands of the minority ruling class, the people’s party can always be made to seem isolated, unimportant, even extraneous. If these tactics still give the appearance of revolution to some after decades of miscarriage, we are justified in replacing them as vanguard[…] Stupidity is not unknown to our long-range political policy makers. Participation in electoral politics organized by the enemy state—after recognizing that the whole process must be discredited as a conditional step into revolution, and particularly participation that tends to authenticate this process—is the opposite of revolution. It’s a tactic for the ultra-rightists. With history as a guide we could never make such monumental errors” (* Blood in My Eye * , p. 25-26, 28).
Jackson, George. Blood in My Eye. 1972. Black Classic Press, 1996.
"Marx and Lenin advocate for supporting progressive political parties in bourgeois elections that communists are NOT competing in." First, "shitty liberal Democrats" are not progressive. Second, as far as I have seen Marx and Lenin have only supported participation in bourgeois elections if a communist party already exists (https://www.youtube.com/watch?v=NX9_kXYMSck). Regardless, conditions in the US are entirely different.
You're wrong on two counts