Bernie Sanders claimed that "expanding the electorate" is a viable strategy for winning the 2020 presidential election.
Even more importantly, they could prove Sanders’s theory of winning elections: expanding the electorate and getting traditionally neglected groups to turn out. Some might call it a political revolution.
"To defeat Donald Trump, the simple truth is we are going to need to have the largest voter turnout in the history of American politics — that’s a fact," Sanders said at a recent rally in Exeter. "That means we are going to have to bring people into the political process who very often have not been involved in the political process."
In an interview during the Nevada 2020 Democratic primary, James Carville was asked "about the risk and down-ballot races under a Sanders nominee". Carville responded, in part, by denying that "expanding the electorate" is a viable strategy for winning the presidential election.
The entire theory that by expanding the electorate  -- increasing turnout so you can win an election [--] is similar to a climate denial. When people say that, they're as stupid to a political scientist as a climate denier is to an atmospheric scientist.
Carville's use of "entire theory" suggests he was not referring solely to Sanders's candidacy.
Some believed that expanding the electorate was a viable strategy for the "rust belt". It may have been successful: Joe Biden Wins Presidency After Recapturing Rust Belt States (this article makes no claim to that effect).
Other Democrats believed [...] that the party should devote its energy to expanding the electorate by mobilizing young people, voters of color and others who look like the country’s changing demographics.
Some claimed that "expanding the electorate" would allow them to win, yet failed. Concerning Texas,
We have a plan to win. One of us, Tory Gavito, runs a data-driven voter empowerment fund that has a track record of expanding the electorate and winning elections.
Is there research to support the claim that "expanding the electorate" is an unworkable strategy per Carville, or does the research dispute the claim?