CDP is complaining about a Abe dirty trick. In various Abe's stump speeches he keeps on referring to CDP leader 枝野幸男(Edano Yukio), as 枝野幸男(Edano Yukio) of the 民主(Democratic Party). The reason why this incorrect name is important is that when the Japanese voter votes, he/she writes the name of the candidate on the ballot for the district race and writes the name or party name on the PR section. When they write the names, acceptable abbreviations are accepted. For example LDP is called 自由民主党 but often called 自民党, 自民 or even 自. So if a voter writes on the PR section "自由民主党" "自民党" "自民" or "自" they call gets counted toward LDP. DPJ or 民主党 was the main opposition party for years until DPJ became DP in 2016. 民主 was always an acceptable name on the PR section for DPJ and for DP...
But 自民党 could also mean Liberal Party, name used by Ichirō Ozawa lead party (twice).
Since Liberal party merged to DPP, it doesn't matter for this election but when it existed 自民党 could mean both LP and LDP.