Friedrich Merz, the conservatives' leader who is tipped to become Germany's next chancellor after a national election set for February 23, sponsored a draft bill with AfD support, breaking a taboo against cooperating with the far-right party.
Around 160,000 gathered at Berlin's Brandenburg Gate, next to the Bundestag lower house, according to the Berlin police. The protesters held banners reading "We are the firewall, no cooperation with the AfD" and "Merz, go home, shame on you!".
Merz, the CDU/CSU's candidate for chancellor, on Friday tried to push the immigration bill in the lower house but failed to secure a majority as some of the deputies from his own party refused to support it.
Their failure to endorse his draft dealt a blow to the authority of Merz, who had pushed for the law despite warnings from party colleagues that he risked being tarnished with the charge of voting alongside the far-right.
Mainstream German parties had previously joined forces to prevent the AfD, which is under surveillance by Germany's security services, from achieving legislative power, something they call a firewall against the far-right.
The draft law would have restricted family reunifications for some refugees and called for more people to be refused at the border. Two-thirds of the public support stronger immigration rules, according to a recent poll.
Merz had argued that the bill was a necessary response to a series of high-profile killings in public spaces by people with an immigrant background. But Chancellor Olaf Scholz's Social Democrats (SPD) and Greens said the proposals would not have stopped the attacks and violated European law.
On Saturday (local time), tens of thousands took to the streets across many other German cities, including Hamburg, Stuttgart and Leipzig, in similar protests against the CDU/CSU and the AfD.
