The impetuous young Kaiser, says John C. G. Rohl, rejected Bismarck's "peaceful foreign policy" and instead plotted with senior generals to work "in favour of a war of aggression." Bismarck told an aide, "That young man wants war with Russia, and would like to draw his sword straight away if he could. I shall not be a party to it." Bismarck, after gaining an absolute majority in favour of his policies in the Reichstag, decided to make the anti-Socialist laws permanent. His Kartell, the majority of the amalgamated Conservative Party and the National Liberal Party, favoured making the laws permanent, with one exception: the police power to expel Socialist agitators from their homes. The Kartell split over this issue and nothing was passed.  As the debate continued, Wilhelm became more and more interested in social problems, especially the treatment of mine workers who went on strike in 1889. He routinely interrupted Bismarck in Council to make clear where he stood on social policy. Bismarck sharply disagreed with Wilhelm's policy and worked to circumvent it.  Bismarck, feeling pressured and unappreciated by the young Emperor and undermined by his ambitious advisors, refused to sign a proclamation regarding the protection of workers along with Wilhelm, as was required by the German Constitution. The final break came as Bismarck searched for a new parliamentary majority, with his Kartell voted from power due to the anti-Socialist bill fiasco. The remaining powers in the Reichstag were the Catholic Centre Party and the Conservative Party. Bismarck wished to form a new bloc with the Centre Party, and invited Ludwig Windthorst, the party's parliamentary leader, to discuss a coalition. Wilhelm was furious to hear about Windthorst's visit. In a parliamentary state, the head of government depends on the confidence of the parliamentary majority and has the right to form coalitions to ensure his policies a majority, but in Germany, the Chancellor had to depend on the confidence of the Emperor, and Wilhelm believed that the Emperor had the right to be informed before his ministers' meeting. After a heated argument at Bismarck's estate over Imperial authority, Wilhelm stormed out. Bismarck, forced for the first time into a situation he could not use to his advantage, wrote a blistering letter of resignation, decrying Wilhelm's interference in foreign and domestic policy, which was published only after Bismarck's death.  Although Bismarck had sponsored landmark social security legislation, by 1889-90, he had become disillusioned with the attitude of workers. In particular, he was opposed to wage increases, improving working conditions, and regulating labour relations. Moreover, the Kartell, the shifting political coalition that Bismarck had been able to forge since 1867, had lost a working majority in the Reichstag. At the opening of the Reichstag on 6 May 1890, the Kaiser stated that the most pressing issue was the further enlargement of the bill concerning the protection of the labourer. In 1891, the Reichstag passed the Workers Protection Acts, which improved working conditions, protected women and children and regulated labour relations.

Answer this question "Shifting what?" by extracting the answer from the text above.
the shifting political coalition that Bismarck had been able to forge since 1867, had lost a working majority in the Reichstag.