When US President Donald Trump makes his much-anticipated first State of the Union address later Wednesday, many eyes will be on the first lady.

Melania Trump has been conspicuously absent from the President’s side since separate claims emerged of Mr Trump’s alleged affair with a porn star and his UN ambassador Nikki Haley.

The State of the Union is typically the most high-profile appearance of the year for first ladies and the White House has tentatively confirmed Mrs Trump will join her husband for the address.

Instead of offering statements in support of her husband in the face of his infidelities in recent weeks, Mrs Trump made louder statements by canceling an overseas trip with the President and instead making solo visits to the Holocaust Memorial Museum and the Trump-owned Mar-a-Lago resort in Florida.

Her relative silence and lone travel came as a Wall Street Journal report claimed adult actress Stormy Daniels was paid US$130,000 ($161,000) shortly before the 2016 election to keep quiet about an affair she had with Mr Trump a decade earlier.

The affair allegedly took place soon after the Trumps were married and while Mrs Trump was pregnant with their son, Barron.

The reports of the affair and subsequent payoff “blindsided” the first lady, according to the New York Times, which reported she was “furious with her husband”.

Ms Haley, one of the leading female figures in Mr Trump’s cabinet, has blasted rumours she is having an affair with the President, describing the claims as “disgusting” and “highly offensive”.

Fuelled by journalist Michael Wolff’s controversial book Fire and Fury, Ms Haley took directly confronted the rumours in an interview with the Politico podcast ‘Women Rule’.

Mrs Trump made no comment on the rumours.

While Mr Trump celebrated his first year in office on January 21, Mrs Trump marked the anniversary by tweeting a single photo of herself on Inauguration Day on the arm of a Marine and made no mention of her husband.

This has been a year filled with many wonderful moments. I’ve enjoyed the people I’ve been lucky enough to meet throughout our great country & the world! 🇺🇸 pic.twitter.com/MMRi72ENd0

— Melania Trump 45 Archived (@FLOTUS45) January 20, 2018

Just days later, on the Trumps’ 13th wedding anniversary, Mrs Trump canceled plans to accompany the President to the World Economic Forum in Davos, Switzerland.

White House watchers will be looking closely for a thaw in the Trumps’ relationship when the President makes his State of the Union address starting 1pm (AEDT).

Mr Trump is expected to take credit for US economic gains over the past year during the address.

White House aides have said Mr Trump would use the televised speech to tout the benefits of a tax overhaul.

“The economy will be front and centre,” White House spokeswoman Sarah Huckerbee Sanders told NBC News.

The atmosphere in the House of Representatives chamber could be tense, however, as some Democratic women plan to attend wearing black in support of the #MeToo movement against sexual harassment.

Some Democrats are also expected to boycott the President’s address.

Mr Trump will also speak against a backdrop of headlines about Special Counsel Robert Mueller’s investigation into whether the Trump campaign colluded with Russia during the 2016 presidential election.

– With AAP