SAN DIEGO — President

Joe Biden’s 81st birthday isn’t for two months. But House Speaker Kevin Mccarthy, the country’s leading Republican, has already sent his gift — an impeachment inquiry that’s likely to backfire and resuscitate Biden’s catatonic reelection campaign.

If Biden gets a boost, it’ll come not a moment too soon for Democratic leaders, who fall into one of two camps: There are those in denial about Biden’s advanced age, low approval ratings and diminished capacity. Then there are those who accept those harsh realities but are scared to express their concerns out loud, because they don’t want to offend the White House or do anything that helps Republicans. Half the Democrats aren’t honest. The other half aren’t brave.

What a predicament. What should Democrats do? Easy. Just be patient and wait for Republicans to step on a rake.

They didn’t have to wait long. By putting on display the reactionary extremism that drives the GOP’S agenda, Mccarthy has come to Democrats’ rescue. It’s not just that the speaker is recasting Biden as a victim. The California Republican is also diverting attention from the president’s age and those polls showing that a majority of Democrats think he is too old to run for reelection.

For his part, Mccarthy claims an impeachment inquiry is warranted because Republicans believe Biden lied about his knowledge of — and possible involvement in — his son Hunter Biden’s business dealings.

There are also concerns that the Biden Justice Department gave Hunter special treatment in a criminal tax investigation, which included a sweetheart plea deal that eventually fell apart when it was rejected by a judge.

In response, Biden’s defenders — liberals in the media who despise Donald Trump — are repeating three White House talking points: First, that Mccarthy is being held hostage by the right-wing House Freedom Caucus. Second, that there is no direct evidence that Biden personally profited from his son’s business ventures with foreign companies. And third, that impeaching Biden is simply payback for Democrats twice impeaching Trump.

There is truth in all three. But it’s also true that Team Biden is moving the goal posts, and White House press secretary Karine Jean-pierre can’t keep her story straight where Hunter Biden is concerned. We’ve gone from Jean-pierre asserting that President Biden never discussed his son’s business with him to a different claim that the president was not “involved” in his son’s business. Those kinds of word games only make matters worse for the White House.

Ditto for Biden’s ham-fisted responses to reporters’ questions. The president claimed that he has “never” talked to his son about his business. Does any parent in America buy that? This parent doesn’t.

It’s worth noting that Mccarthy’s impeachment gift was not very original. It resembled the one given to Trump when prosecutors — state and federal — filed, in less than five months, a total of 91 criminal charges against him. The counts include being in possession of classified documents and conspiring to overturn the results of the 2020 election. As the charges piled up, some in the media who don’t want to see Trump return to office all but pleaded with prosecutors to stop indicting him. Their concern was that, with every new set of charges, Trump was getting stronger and more popular with a big chunk of the Republican Party. Prosecutors pulled off something that many of us didn’t think was possible: By making Trump into a victim, they inspired more people — even beyond the MAGA base within the GOP — to feel sorry for him.

It’s likely this will happen to Biden, too. Just when Democrats were running out of ideas about how to get the president to step aside or get voters excited about him, the threat of impeachment is like a rainstorm during a drought. It’s a Washington miracle! For those of us in the center, this episode serves as proof that the political parties are — despite their claims to the contrary — more alike than different.

Politicians rub elbows with one another, and so they get to watch one another make mistakes. And then, curiously, instead of learning from those mistakes, they will often repeat them.

If they impeach Biden, as seems almost certain at this point, Republicans in Congress will take someone who they claim is a criminal and turn him into a martyr.

Why does that sound familiar?