Integrity is the second principle of political life as discussed here. No financial obligation should be accepted if it undermines the politician's position.
Once again, the wording of the principle raises difficulties. What does it mean, to undermine a politician's position? In my view, the simple acceptance of a financial contribution says nothing about a politician's integrity. Jesse Unruh said it best ( this is the cleaned up version) "If you can't take their money and vote against them, you don't belong in politics."
The real issue is conflict of interest. Is there a quid pro quo ? If a politician takes out a loan to buy a home, there is no conflict of interest. If he or she accepts a personal loan from someone with a policy agenda, there is probably a conflict.
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