Most media cover Republican "civil war", ignore Democratic "civil war"

There is indication that Democratic Party primary challengers are pushing incumbent candidates to embrace leftist policies that are popular within the Democratic Party, but are not popular among the general electorate. Meanwhile, "mainstream" media outlets love to point to Republican primary challengers, who are pushing Republican incumbents to the right. The difference is that the Republican candidates are moving toward positions that are popular with the general electorate (for example, John McCain moving to support the immigration law in his own state). The Wall Street Journal shines some light on this topic:

Given the obsessive coverage of the Republican "civil war," you may not realize Democrats are also feuding. Angry and disappointed that their president and Congress has not done more, the party's liberal base is throwing itself into the primaries, pushing the party to the left even as the country moves right.