US President Donald Trump will try to sell voters on the economy during his State of the Union address on Tuesday, despite suffering a series of stinging blows ahead of crucial midterm elections this year.

After a breakneck first year back in power, Trump will declare to Congress that America is "strong, prosperous and respected" as it prepares to celebrate its 250th anniversary, the White House said.

Trump will "proudly tout his administration's many record-breaking accomplishments" and lay out an "ambitious agenda to continue bringing the American Dream back for working people," Press Secretary Karoline Leavitt said.

The 79-year-old Republican himself warned on Monday that the first official State of the Union of his second term was "going to be a long speech because we have so much to talk about."

The world will meanwhile be watching for hints from Trump about possible military action against Iran, with a huge US military build-up pressing Tehran to make a deal on its nuclear programme.

Trump will address foreign policy, insisting on what his administration calls a "peace through strength" strategy following a series of military interventions including in Venezuela, US media reported.

But the speech comes at a politically fraught moment for Trump, amid consistently low approval ratings and days after a Supreme Court ruling that struck down the tariffs at the heart of his economic agenda.

Speaking in front of the very same justices he has branded "fools and lapdogs," Trump is expected to issue a strong defence of his tariffs.

Trump's poll ratings are a worry for Republicans and the White House ahead of November's midterm elections.

If they lose their wafer-thin majority in the House it could paralyse the rest of Trump's second term – and put him at the risk of a possible third impeachment.

Trump's economic message will focus on what he claims is success in cutting inflation, boosting jobs and manufacturing, and restoring what he calls a "Golden Age" of America.

But the billionaire president has yet to convince many voters who are still worried about the cost of living – something he has repeatedly dismissed as an "affordability hoax."

A Washington Post-ABC News-Ipsos poll published on Sunday showed his approval rating at 39 percent. Only 41 percent approved of his handling of the economy overall, and just 32 percent on inflation.

Trump's other signature policy, his promise to deport undocumented migrants, is more popular.

But polls show most Americans think the crackdowns in which two US citizens were shot dead last month in Minneapolis have gone too far.

"It comes at a very important time in his presidency. He's under water politically in general and on the important issues of the economy and immigration," said Aaron Kall of the University of Michigan.

Democrats are lining up responses including boycotts and silent protests for the address – mandated by the US Constitution, which says that the president shall "from time to time give to the Congress information of the State of the Union."

Adding to the interest will be the guests that both Republicans and Democrats bring to watch the address from the gallery, part of a long tradition.

Trump has invited the US men's ice hockey team after they won Olympic gold. But the women's team said they were declining Trump's invitation, US media reported, a day after the president joked in a call to the men's team that he would be impeached if he didn't invite the women.

Two Democratic members of the House of Representatives said they were bringing as guests the family members of a victim of disgraced late financier Jeffrey Epstein.

Trump has denied any links to sex offender Epstein but the scandal continues to nag at his presidency. (AFP)



Edited by Robert Kemp