Former President Barack Obama will gingerly step into the public fray on Tuesday night, after weeks of quiet grumbling from some demoralized Democrats for what they say is his silence in the face of a frontal assault on liberal America by the Trump administration.

Mr. Obama will participate in a discussion in Hartford, Conn., with Heather Cox Richardson, a popular liberal writer and historian, at a moment of deep uncertainty and volatility for his party, the country and the world.

Domestically over the past week, a Democratic senator was forced to the ground and handcuffed after trying to ask a question of a cabinet secretary at a news conference; a Democratic governor was threatened with arrest by President Trump and with being “tarred and feathered” by the House speaker; and a Democratic state lawmaker in Minnesota and her husband were assassinated in shootings that wounded another Democratic legislator and his wife.

Overseas, speculation has grown that Mr. Trump could order the United States to openly enter the escalating war between Israel and Iran by bombing a key Iranian nuclear facility.

It remains unclear whether Mr. Obama will issue a strong statement on Tuesday evening about any of the violence and chaos of recent days. He has largely shied away from offering a running commentary on politics or on Mr. Trump, declining to take a role as a leader of the opposition. Some Democratic officials and voters have grumbled about his reticence, wanting him to offer more vocal and frequent criticism.

Mr. Obama will be paid for his appearance in Hartford, at the Bushnell Center for the Performing Arts. Like many former officials, he has participated in a series of similar paid conversations at universities, civil society groups and other public forums over the years.