But senior figures in the two junior coalition partners, the Greens and the Free Democrats, have demanded that the chancellor change course.

The Free Democrats are likely to back heavy arms deliveries at a party conference this weekend, while the Greens’ Annalena Baerbock, the foreign minister, has said “Ukraine needs heavy weapons”.

Christian Lindner, the finance minister and the leader of the Free Democrats, said on Saturday that “we must do everything in our power” to help Ukraine, including sending heavy weaponry, but added that Germany needed to put its own security first.

“What is possible … must be undertaken pragmatically and quickly, together with our European partners,” he said.

The CDU’s motion calls on the government to “immediately and noticeably intensify weapons deliveries” and demands that the government delivers battle tanks and artillery from the German army’s arsenal.

If the Greens and the Free Democrats were to back the motion, it would throw the four-month-old government into a deep crisis and possibly lead to the downfall of Mr Scholz.

Political observers say the chancellor would then be faced with a humiliating about-face on his current strategy or would have to call a vote of confidence to test whether he still holds a majority.