It’s Christmas week, and America is in the midst of the witness wars. Sen. Chuck Schumer issued ­another demand Sunday for more witnesses and documents as impeachment moves to the Senate. He is undercutting House Democrats’ boasts of a “rock-solid case” against President Trump. If the case is so solid, why the need for more witnesses? Truth is, as Senate Majority Leader Mitch McConnell says, Democrats have the “thinnest basis” for impeachment “in American history.”

And Democrats know it. House Speaker Nancy Pelosi is refusing to send the articles of impeachment to the Senate to begin the trial. She claims she is pressuring McConnell into calling additional witnesses. Her arm-twisting is “absurd,” McConnell says. “Frankly, I’m not anxious to have the trial. If she thinks her case is so weak she doesn’t want to send it over, throw me into that briar patch.”

He suggests that “the prosecutors are getting cold feet.”

McConnell is proposing that House Dems and then White House lawyers make their arguments to the senators. The trial could be wrapped up in a couple of weeks, unless senators ­decide after hearing the arguments that they need to hear witnesses.

But Schumer wants more witnesses guaranteed up front. After 17 witnesses, 8,000 pages of testimony and legal arguments, 106 House staff members working full-time, six high-paid outside lawyers and millions of dollars spent to produce a party-line vote in the House to impeach, Senate Democrats are hankering for another long, drawn-out spectacle.

They aren’t outsmarting anyone except themselves. The witnesses they are seeking are unlikely to show up, no matter what political tricks the Democrats try. Meanwhile, national support for impeachment is steadily falling, and every day Democrats spend on impeachment lessens their chances of unseating Trump in November.

Schumer wants four White House officials, including acting chief of staff Mick Mulvaney and ex-national security adviser John Bolton, to testify. But Democrats lost their chance to bring in these witnesses by voting to impeach.

Close advisers to any president are protected by executive privilege. That isn’t a Trump invention. Presidents, including George Washington, have said “no” when Congress demanded access to evidence of White House decision-making. President Barack Obama’s attorney general, Eric Holder, was especially aggressive about asserting privilege.

The Constitution creates three equal branches of government, and the president has a duty to protect his branch from congressional overreach. When these two branches clash, the federal courts are the referee.

That’s true generally, but House Dems took a shortcut. When Trump ­refused to provide certain witnesses, House Intelligence Committee Chairman Adam Schiff balked at “a lengthy game of rope-a-dope with the courts.”

It was a short-sighted move. Once House Dems voted to impeach, they lost any chance to have the federal courts order Trump’s advisers to appear. The Supreme Court ruled in 1993 that judges cannot interfere in impeachment trials, because the Senate has “the sole power” over them.

In fact, minutes after the vote, federal appeals judges asked Congress to show why its case to compel the testimony of former White House lawyer Don McGahn isn’t abruptly ended because “the articles of impeachment render the case moot.”

With the courthouse doors slammed shut on impeachers, they are trying to strong-arm McConnell into calling witnesses. Yet they are forgetting that McConnell can’t negotiate away executive privilege. It’s not his to surrender.

Meanwhile, Pelosi sees the disaster ahead. She has invited Trump to deliver the State of the Union address to Congress on Feb. 4, knowing he will still be president. He will report a booming economy, record-low unemployment and beneficial trade deals with China, Mexico and Canada. Plus a federal judiciary rescued from activists.

Even last week, as Democrats fretted over impeachment, McConnell pushed through 13 more Trump-nominated judges.

Democrats impeached Trump to damage his re-election chances. But their conduct so far has made impeachment a stain on them. Ultimately, voters, not politicians, will decide Trump’s fate. That’s where the decision rightly belongs.

Betsy McCaughey is a former lieutenant governor of New York.