One alternative tactic, adopted yesterday by Paul Ryan, is to suggest instead that Trump is not a true conservative at all. According to this view, Trump and his policies are therefore by definition ruled out as deserving of the party's support. This argument has yet to show much promise, however, in stopping Trump's rise among Republican voters.
Today, the Wall Street Journal editorial page takes another tack. The meat of the piece is a direct criticism of Trump's proposal to ban Muslims from traveling to the United States, which the Journal finds both counterproductive to the fight against terrorism and, euphemistically, certain to "face constitutional scrutiny." But this volley against Trump is wrapped at both ends inside a denunciation of Barack Obama's administration, which the Journal holds directly responsible for Trump's rise. "The oldest truism in politics," says the Journal, "is that demagogues flourish in the absence of leadership."
This particular anti-Trump argument is echoed by Ben Domenech at the Federalist, who treats Trump's candidacy as the "greatest political legacy" of Obama's presidency, such that a piece critical of Trump is entitled "Welcome to Barack Obama's America." Domenech views Obama's failures as extending beyond foreign policy and the war on terror to encompass the erosion of faith in government and even the rise of political correctness—a line of argument extended further in the same publication by Rubio advisor Paul David Miller, who accuses "progressivism" itself of provoking a Trump-led backlash that Miller sees as threatening the health of the Republican Party.
[UPDATE: Even Jeb Bush got in on the fun this afternoon:]
Jeb Bush calls Donald Trump "basically Barack Obama - the other version of it" -- trying to make point that Trump is a divisive force— Kasie Hunt (@kasie) December 9, 2015
If you want to trash Trump but don't want to sound like a lefty, the "blame The Donald on Obama" approach has an obvious appeal, regardless of its underlying validity. One pictures a group of anti-Trump Republicans at the White House gates, shaking fists that clutch Trump's current poll numbers, yelling "Look at what you're making us do!" at the president inside.