Washington (AFP) - Joe Biden may have preached unity but new House Speaker Kevin McCarthy's frosty expression and the Republican jeers throughout the State of the Union speech told the story of a partisan night.

In a potent reminder of how the balance of power has shifted, Biden delivered his annual address -- and perhaps his pitch for another term in the White House -- in the shadow of Washington's top Republican.

At the president's prior visit to the rostrum, under unified Democratic government, the two parties cheered together as he vowed that Russia's newly-launched invasion of Ukraine would not stand.

But in the now Republican-led House of Representatives, the temporary truce traditionally observed during the speech was loudly ignored -- in a stark reminder that Washington politics is, at its core, a blood sport.

And with 80-year-old Biden mulling the launch of his reelection bid within months, the stakes could hardly have been higher. 

It all started cordially enough, with both sides clapping for the party leaders and McCarthy smiling as Biden ad libbed: "Speaker, I don't want to ruin your reputation, but I look forward to working with you."

Political kabuki

Republican lawmakers -- who are pressing numerous investigations into Biden -- glowered at the president for the most part, occasionally muttering to a neighbor.

McCarthy had reportedly asked his troops to refrain from heckling, and many settled for staring at their phones.

Stage left, Democrats leapt to their feet and cheered every punchline, dutifully but boisterously.

But when Biden changed gear to criticize the Republicans -- and especially his predecessor Donald Trump -- the muttering gave way to howls of outrage and unrestrained booing. 

There were shouts of "liar" in a section about potential Republican cuts to social security payments and later, "it's your fault" when Biden turned to the opioid crisis.

This ritualistic back-and-forth is nothing new, but the political kabuki comes with an air of menace in post-insurrection Washington.

Security is always tighter for the State of the Union but since the 2021 assault on the Capitol by Donald Trump's supporters the complex has been turned into a fortress for big occasions.

A seven-foot (2.13-meter) black metal fence ringing the complex was a grave reminder of the stakes in the 2024 presidential election, with political violence on the rise.

The Capitol, a neoclassical citadel of US democracy on the edge of Washington's National Mall and a major tourist attraction, was closed to the public. 

Inside, police dogs skulked with their handlers in almost every corner.

Star power

U2 frontman Bono represented the kind of star power that can bridge political divides -- who doesn't like anthemic Irish rock? -- but other invitees were pawns in the culture wars.

The guest list included a hero who intervened in a mass shooting in California and the families of African American victims of police violence -- the latest, Tyre Nichols, who died just a month ago.

Leftist lawmakers wore buttons marked "1870" -- the year of the first known police killing of an unarmed, free Black man.

And lawmakers gave a standing ovation to Nichols' parents, RowVaughn and Rodney Wells, in one of the rare bipartisan moments of the night.

But some Republicans also wore lapel pins in the shape of the AR-15 style rifle used in numerous school shootings, a truculent affirmation of the right to bear arms. 

Biden's speech was more focused on kitchen table issues than soaring rhetoric, but it was delivered with gusto and allowed him to take a lengthy victory lap for two years of hard-fought accomplishments, many of them bipartisan. 

"To my Republican friends, if we could work together in the last Congress, there is no reason we can't work together in this new Congress," he said.

A handful of Republicans clapped and even stood but most glared silently at the president. McCarthy remained riveted to his seat, expression inscrutable.