Indiana Gov. Mike Pence.  (Aaron P. Bernstein/Getty Images)

Indiana Gov. Mike Pence may have had the worst launch of a vice presidential candidate since fellow Hoosier Sen. Dan Quayle (R-Ind.) played the part of the deer caught in the media headlights in 1988. He better get used to the Trump roller coaster and being the newest in a long line of Republicans forced to sound dopey in order to support Trump’s daft ideas. Here is why:

1. He cannot get up to speed on a variety of key issues by seeking out expert advice. Experts with actual facts would just make Pence’s dilemma worse. He’d have to learn two versions: the sane, fact-based policy and then Trump’s view of the world. No knowledgeable adviser would tell Trump we can build a wall and force Mexico to pay for it, yet Pence will need to adopt this and other Trumpian fantasies. That leaves Pence holding the bag when interviewers and debate moderators grill him on Trump’s ideas, making Pence seem silly.

2. He doesn’t know Trump. One cannot expect Pence to be a mind reader and stay in sync with the mercurial Trump. Wait for lots of “He misspoke” corrections.

3. Pence is at odds — or was at odds — with Trump on too many issues. Be it foreign policy, negative campaigning, trade, defunding Planned Parenthood, entitlement reform or a dozen other items, Pence is a staunch, polite conservative. Trump is neither.

4. Trump makes everyone else seem small. He repeatedly humiliated his “friend” New Jersey Gov. Chris Christie (making Christie call him “Mr. Trump,” stand silently behind him and be strung along as a possible running mate). At the VP rollout on Saturday, Trump’s focus on himself for over 20 minutes conveyed one thing: Pence is not important. Trump’s ego does not allow him to show respect for others or be generous in praise. Pence will seem a lot smaller at the end of the campaign.

5. Pence doesn’t have foreign policy experience either. (He was on the House Foreign Affairs Committee, but that’s about it. He cannot even see a foreign country from his back yard.) The Trump ticket’s lack of national security acumen will persist.

6. Pence ably supported the Iraq War. Trump wants to beat Hillary Clinton over the head with her vote for the war and blame Republican George W. Bush for “lying” about weapons of mass destruction. He still falsely claims he was against the war all along. If he pursues that message, he’s indicting his own VP.

Pence surely will have company in the “diminished by Trump” category. One of the most tragic aspects of Trump is how intellectually dishonest and weak he has made otherwise respectable Republicans seem.

The irony is that had Pence run himself for president in 2012 or 2016, he might have done quite well. We saw this year, for example, how effective he was in dismissing Trump’s Muslim ban. The very things that put him at odds with Trump — consistent conservatism, fiscal frugality, hawkishness on foreign policy, personal rectitude — would have served him well. Pence is a straight arrow, a devoted husband (one wife, of over 30 years) and hasn’t sued, bullied and scammed working-class people. He’s going to be asked to defend a great many things he finds personally offensive (e.g., Trump’s bigoted language). Remind us again: Why’d he take the job?