President Obama has signaled that he’ll break with tradition and speak out on political issues after leaving the White House — almost surely in opposition to his successor. We hope he thinks this one through again.

In Peru on Sunday, Obama refused to commit to sitting on the sidelines. On core issues “about our values and our ideals,” he said, “I’ll examine it when it comes.”

He was more blunt to Organizing for Action activists: “You’re going to see me early next year, and we’re going to be in a position where we can start cooking up all kinds of great stuff.”

He surely realizes that speaking out after January puts at risk his current popularity, and is willing to pay that price to defend his principles. Heck, for all his 2008 talk of having a “post-partisan” White House, he wound up becoming one of America’s most partisan presidents ever.

But that didn’t work out too well: His leadership has cost his party dearly in Congress and in the states — leaving Democrats in their worst shape in nearly a century.

Yes, the press still adores him, and desperate Dems may welcome his help. Thing is, he hasn’t been great at selling anything except himself.

His pitch for ObamaCare never swayed the public — Democrats passed the law despite its unpopularity, and have been paying for it at the polls ever since. Nor did he ever persuade the voters to love the Iran deal, his other big “legacy” item. And Hillary Clinton lost despite Obama’s every campaign effort.

Meanwhile, Obama risks drowning out the new voices Democrats sorely need if they’re to bounce back. New stars can’t rise if the old ones refuse to leave the stage.

He’d also burden the party not just with old issues, but old attitudes.

Donald Trump won — first over 16 Republicans, then over Hillary Clinton — because voters want change. They rejected both sides of the divisions that have defined Washington for decades.

From giving job interviews to harsh critics like Mitt Romney, to dropping talk of a special prosecutor for Hillary Clinton, the president-elect is signaling that he wants to move beyond old battles. After all, Trump is no conservative ideologue, but a dealmaker.

Maybe Democrats will be able to advance their agenda by working with him on some things while they rebuild their brand — if they’re not held back by an elder statesman who can’t let go of the battles of his glory days.

Obama was often accused of running a “permanent campaign.” Leaving office would be a wise time to finally end it.