Joe Biden’s weaknesses are obvious, but the State of the Union last Thursday and the president’s $7.3 trillion budget proposal this week are reminders of just how tough he can be.

Biden isn’t simply an old politician, he’s an old-fashioned one — the kind who believes in buying the vote.

He tried it in the 2022 midterms with a student-loan forgiveness push that had little chance of surviving the courts.

But it didn’t need to; all that mattered was convincing young voters they had a vested interest in the Democrats’ fortunes.

The Supreme Court shot down most of the scheme last year, but Biden took time in the State of the Union to remind indebted graduates of what he did get through.

Biden is an absolute master of the traditional pork-barrel method of courting constituencies.

He learned something in his 36 years in the Senate, not least about the techniques that made Democrats the dominant party in Congress for decades after the New Deal.

When they ruled the House of Representatives for all but four years between 1931 to 1994 — and controlled the Senate for all but 10 — Democrats sold themselves as a party of government services, entitlements and payouts.

The culture war was a loser for them, as George McGovern’s 49-state blowout loss to Richard Nixon in 1972 proved.

McGovernites conquered the party from within, and today not even a Democrat as cunning as Biden can afford to defy identity politics.

He can downplay it, however — and Biden has lately made an appeal to economic identity, as well as specific interests, a vital component of his reelection rhetoric.

Biden boasted of bringing back manufacturing jobs that pay six-figure salaries to workers without college degrees.

Manufacturing states like Pennsylvania, Wisconsin and Michigan made Donald Trump president in 2016 — and snatching them away from Trump won Biden the White House four years later.

Biden might not reverse the exodus of Americans without degrees into the ranks of the GOP, but he hopes to blunt the Republicans’ advantage.

Yet Biden has another front to worry about — the crumbling of his party’s near monopoly on key non-white demographics.

A poll recently found 23% of Black voters surveyed would vote for Trump if the election were held immediately.

And Trump would win a plurality of Hispanics, 46% to Biden’s 40%.

The erosion of Democrats’ nonwhite support is gradual but very real.

An analysis of the 2020 election by the Democratic data company Catalist noted a 3% drop in Biden’s share of the Black vote compared to the proportion won by Hillary Clinton in 2016, and a decline of 8 points in comparison to Clinton’s performance among Hispanics.

Biden did, however, improve on Clinton’s numbers with whites, both those without a college degree (by 1 point) and those who were college graduates (by 4 points).

Can Biden offset the widening loss of black and Hispanic voters by expanding his share of whites, particularly among those who didn’t attend college?

Identity politics complicates this; college-educated white liberals will not let it go.

The latter-day McGovernites are affluent and hardly need the services that Democrats of yesteryear proffered; they really do want amnesty (for illegal immigrants, rather than the draft dodgers of the ’70s) and abortion, not protections for domestic industry.

Hence Biden’s apology for referring to a murderer as an “illegal” immigrant during the State of the Union.

That term is taboo in the language politics of the left.

Biden knows what he has to do to win — but the educated whites who are the backbone of his party have little in common, culturally or economically, with the lower-class whites whose interest is in work, not woke.

Growing numbers of Black and Hispanic voters are also deserting the white liberal party.

But Biden is not to be underestimated, and if Trump is going to beat him, he has to take seriously the Democrat’s determination to outbid him in an auction for votes.