I think Wes Yang is correct. Persons unknown decided that they would perform a 180° turn on this issue and many others, including immigration.

We all witnessed this happen in real time. It was not a slow drip or a boiling of the frog. It was sudden, abrupt, consciously coordinated across every organ of what coalesced into a single integrated messaging apparatus. All those who deny or obfuscate this central fact of American public life are engaged in conscious deceit.

This post leads to an opinion piece in the NYT, "‘I Wouldn’t Say the Democrats Are in Good Shape’". Here's an excerpt:

In October, the group behind the centrist Democratic WelcomePAC issued “Deciding to Win,” an analysis of “election results, hundreds of public polls and academic papers, dozens of case studies, and surveys of more than 500,000 voters” that found that “since 2012, highly educated staffers, donors, advocacy groups, pundits and elected officials have reshaped the Democratic Party’s agenda, decreasing our party’s focus on the economic issues that are the top concerns of the American people.”

The authors tracked key word usage in Democratic platforms from 2012 to 2024 and found the frequency of the word “hate” increasing by 1,323 percent; “white/Black/Latino/Latina” by 1,137 percent; “L.G.B.T./L.G.B.T.Q.I.+” by 1,044 percent; and “equity” by 766 percent.

Over the same period, usage of “father/fathers” fell 100 percent; “crime/criminal” by 30 percent; “responsibility” by 83 percent; “middle class” by 79 percent; and “veteran” by 31 percent.

Finally, in November, Politico’s Elena Schneider reported the findings of a 21-state research project funded by Democracy Matters involving polling, dozens of focus groups and message testing.

“Working-class voters see Democrats as ‘woke, weak and out of touch’ and six in 10 have a negative view of the party,” she wrote . . .