Alexei Navalny's widow Yulia faces daunting challenge in Russia

For years, Yulia Navalnaya was a near-constant presence by her husband's side. At political protests and court hearings she would be there, often holding his hand.

In 2020 when Alexei Navalny was poisoned with a nerve agent, it was Yulia who pushed for clearance to fly him abroad for life-saving treatment.

And now he has died alone and far from her in an Arctic prison.

She blames Russian President Vladimir Putin for that and is calling on Russians to stand beside her now in fighting him.

The video statement Yulia Navalnaya posted online on Monday was a deliberate, and dramatic, step into the political spotlight. Her love for her husband is so strong, and her grief still so raw, that the recording is painful to watch in parts.

But it is very compelling.

Navalny's widow describes herself as being torn in two, her heart broken. But it's her fury that's driving her to continue her husband's cause.

She says she wants to realise his "beautiful Russia of the future", so that his "unthinkable" death won't have been in vain.

For some Russians who oppose Mr Putin, and are very despondent right now, the speech will have been uplifting.

Until this moment, Yulia Navalnaya was reserved and distant. But the video reveals her to be a woman of enormous inner strength.

Her loss - and her love - lend her clear moral authority and she is engaging.

There is precedent for strong women stepping in for absent men.

It happened most notably in neighbouring Belarus, where the authoritarian Alexander Lukashenko so underestimated Svetlana Tikhanovskaya, he allowed her to register for the 2020 presidential campaign when her husband Sergei Tikhanovsky was arrested.

That sexism nearly cost Mr Lukashenko his exceedingly long grip on power. When he declared a landslide victory, Ms Tikhanovskaya brought huge crowds on to the street shouting about a rigged vote.

She had to flee abroad after a warning from the KGB and now acts as a "president" in exile.

Evgenia Kara-Murza has also taken on a global role.

When her husband was poisoned in Moscow in 2015 and 2017, Evgenia fought to stay by his side in hospital, guarding him "like a dog".

At the time, Vladimir Kara-Murza was campaigning for Western leaders to tighten sanctions on Mr Putin's people.

Then in 2022, he was arrested for condemning Russian war crimes in Ukraine and convicted of treason.

Evgenia, a translator by profession, now spends most of her time continuing her husband's campaign for sanctions - as well as calling for his freedom - in Western capitals.

Yulia Navalnaya could take on a similar role.

She's already addressed EU foreign ministers, who issued a statement of "outrage" at Navalny's death. They declared that the "ultimate responsibility" lay with Mr Putin and promised "further costs", as yet unspecified.

But leading opposition forces within Russia is harder to see.