Once collaboration with the GMD was decided upon, Mao’s main concern was how to use communist troops in the War of Resistance. While the CCP was prepared to make declarations about the democratization of the GMD regime, Mao’s concern was how to preserve military strength, avoiding needless sacrifice. Some were concerned, however, that too passive a response would undermine sympathy for the CCP. Ultimately a policy of self-preservation and expansion was accepted.
The adoption of the united front did bring the simmering conflict between Mao and Wang Ming to a head and this was the last major inner-party struggle before Mao exerted power over the party as a whole. Mao working within China felt that the GMD was incapable of leading the War of Resistance and that the CCP must retain its independence and initiative. By contrast, Wang Ming was much more amenable to the policy of collaboration and was denounced for promoting the policy of "All Through the United Front." On 29 November 1937, Wang Ming and seven other members of the CCP Mission to the Comintern, including Kang Sheng and Chen Yun, arrived in the CCP headquarters at Yan’an. Wang was given a warm welcome. Mao meeting him for the first time, purportedly said Wang was "a blessing from the sky." But Wang also immediately challenged Mao as the dominant ideological force in the party. When Wang reported on what kind of position ought to be taken vis-à-vis the united front, Mao is supposed to have voted to accept the report in part since it appeared to reflect Stalin's views. But Mao had quite other ideas about how the united front ought to be conducted.
Mao had to defeat Wang Ming politically and then present an approach to theory that would not only appropriate the united front as his but also undermine Wang Ming's credibility. This latter objective was difficult to achieve because "Stalin had instructed Wang Ming to overcome the ‘leftist deviation’ in the Party without directly contesting Mao's authority."
To deal with the situation created by these new arrivals, the Politburo held a Conference from 9 to 14 December, at which Wang Ming won the support of the majority and established his influence, although his power base remained weak. Wang delivered the keynote speech to the conference while Mao remained silent. Wang’s 27 December article called for improving the unification of all work in what became to be known as the policy of "everything through the united front." This contrasted with Mao's calls for "independence and initiative." Wang clearly felt that his was the best way to develop CCP activities outside of the Border Region. While Wang acknowledged that problems still existed with the GMD, he felt that the foundations had been laid for a solid anti- Japanese national united front. This cooperation would be long-term, continuing after the war during a period of national reconstruction. He also called for the united front to be extended beyond the two parties to mobilize effectively other groups for resistance. Although Wang accepted that CCP members could join the GMD government, he maintained that the Eighth Route Army must retain its independence.
The conference’s resolution congratulating the CCP Mission to the Comintern for its work in formulating the new policies for the anti-Japanese united front appeared to boost Wang's pre-eminent position. In fact, organizational changes strengthened Mao's