Donald Trump’s embrace of authoritarian tactics – and leaders – has dealt a body blow to activists struggling against repressive regimes across the globe, campaigners have warned, as the US president prepares to welcome China’s strongman ruler, Xi Jinping, to his Florida estate.

Xi, the architect of a severe political clampdown at home, will be the second authoritarian Trump leader has hosted this week, following his controversial endorsement of Egyptian president Abdel Fattah el-Sisi at the White House on Monday.

“We agree on so many things,” the US president said of Sisi, who has been accused of jailing opponents, suppressing protests and overseeing a deadly military crackdown that left hundreds dead.

Xi, with whom Trump will hold two days of potentially thorny talks focused on trade and North Korea, also faces a litany of accusations over his human rights record. In the nearly five years since he took office, activists say China has been plunged into the harshest period of political repression since the days after the 1989 Tiananmen crackdown.

Campaigners and political opponents have urged Trump to speak out against Xi’s crackdown – which has targeted feminists, academics, publishers and top human rights lawyers – when the pair meet at Mar-a-Lago on Thursday.

“It is unacceptable for President Xi to get a pass on human rights,” Republican senator Marco Rubio said, pointing to more than 1,000 political and religious prisoners he said were languishing in Chinese jails.

However, Nicholas Bequelin, Amnesty International’s East Asia director, said Trump’s open contempt for the judiciary and support for policies “in absolute and complete contradiction of human rights obligations under international law”, such as his travel ban, meant the days when Washington could effectively lecture countries like China on human rights were over.

“When a repressive government chooses to send someone to jail … they make political calculations about the benefits and costs of putting that person away,” he said.

“The fact that the US seems to be abandoning any kind of role in maintaining a consistent message on human rights and protesting human rights violations affects the calculations of these governments. They are just going to think there is no price to pay for political repression. So it will embolden them and at the end of the line human rights defenders in China will pay a heavier price … It is not going to be pretty.”

Bequelin said that with Trump in the White House, Beijing would feel “relief that there is no strong moral authority coming from the US anymore”.

Margaret Huang, the executive director of Amnesty International USA, said that despite having been in office for less than 100 days, Trump could already boast “a significantly dismal human rights record”.

Trump’s silence over Xi’s sweeping crackdown and attempts to transform his own “hateful” campaign rhetoric into policy suggested he had decided to de-emphasise human rights issues both at home and abroad.

“Human rights around the world are under increasing threat today and without bold, principled leadership we are heading in a very dangerous direction,” Huang added.

Recent months have seen Xi attempt to contrast himself with the erratic commander-in-chief, stepping forwards as a champion of globalisation and the fight against climate change.

But Bequelin said he was troubled at how Trump’s apparent abdication of global leadership meant Xi would go into this week’s talks feted as the more responsible figure.

“The optics of this meeting, frankly, is going to be that Xi Jinping is the adult in the room. But the next question is: what kind of adult?” Bequelin said.

“He is the leader of an almost completely unaccountable political structure domestically; a country where you have no rule of law, no elections, no religious or political freedoms, no free press and so on. It is wishful thinking to hope that greater Chinese leadership over global affairs would somehow turn out to be something different to what China is at home.”

Despite widespread despondency over Trump’s unwillingness to champion human rights, victims of Xi’s crackdown are urging him to publicly challenge his guest.

Wang Qiaoling, the wife of jailed attorney Li Heping, said she hoped Trump would demand the release of prisoners such as her husband “with no strings attached”. “If Trump knows what is happening in China, he will take action,” she said.

Calls to publicly raise human rights issues are likely to fall on deaf ears, however. “Those are the kind of things that I believe progress is made privately,” White House press secretary Sean Spicer told reporters.

Last month, it emerged the US had declined to sign a letter criticising China over the alleged torture of human rights lawyers and activists, in a break with past practice.

Ashley Townshend, a scholar at the University of Sydney’s United States Studies Centre, said it was possible Trump would feel “some sense of camaraderie” towards China’s authoritarian leader. “There is something in Xi that Trump will find attractive. Trump respects powerful strongmen. He respects strength.”

Bequelin said activists fighting repressive regimes would not throw in the towel simply because they could no longer count on the White House’s support.

“When you live near a lake and you see the lake turn red [you] are not thinking about whether the great arc of the history of human rights is going in the right direction or not. You just want your kids not to be poisoned,” he said.

“[But] there is no doubt about it: abandoning human rights means abandoning human rights defenders. Abandoning people who play a positive role, and are very often the antibodies of the societies they live in, will make for a more unstable world in the medium and the long term.”