A legislator can be a seat-warmer and hide in a crowd.
This is all irrelevant - any 'legislator' running for President has not been a backbench seat warmer.
Two words: John Kerry. Dude's photo is in the dictionary as an example of a "seat warmer." Not that I mind. We don't need a Teddy Kennedy mini-me doubling the volume of bad bills from the Massachusetts Senators.
There have been several examples of experience as relates to POTUS in previous posts.
Obama lacks experience in both quantity and quality. He hasn't been around long, hasn't done much, and what he has done has less applicability than most other serious contenders. If experience has any relevance to the position of POTUS, by any measure, Obama has little of it.
There are other candidates that also lack experience. Most of them are not in the race and are running vanity campaigns. Of all the top tier candidates from either party, Obama is has the slimmest resume for the POTUS job.
Foreign relations, security and the ability to preside over the entirety of a nation-state would seem to be the three primary roles of a President - none of which is translatable to the 'executive experience' of running a state....
Actually, the primary role of POTUS is to uphold the COTUS and the primary role of a governor is to uphold their state's constitution.
Also, the northern & southern border states have quite a lot to do WRT foreign relations and security. The governor of Alaska has to deal with Russia, as well, considering the fishing waters and close proximity.
Security is a no-brainer. Governors preside over state police agencies and county & local agencies are subject tot the state's constitution and laws.
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One can believe the "experience argument" BS, but they will be operating outside of reality. I am reminded of the old joke about the economist stranded on a desert island with a bunch of canned goods and no can opener, "To solve this problem, I will first assume a can opener..."
Works fine in the classroom & midnight bull session, but doesn't do so well in reality.