Who is responsible for vetting the candidates?

The blog "The Right Side of Life" has an interesting post today entitled "Is the Onus of Presidential Qualification on the Parties?". This article contains a link to the DNC Delegate Selection Rules, where on page 18 it is stated that:

K. 1. Based on the right of the Democratic Party to freely assemble and to determine the
criteria for its candidates, it is determined that all candidates for the Democratic
nomination for President or Vice President shall:

a. be registered to vote, and shall have been registered to vote in the last
election for the office of President and Vice President; and

b. have demonstrated a commitment to the goals and objectives of the
Democratic Party as determined by the National Chair and will participate
in the Convention in good faith.

2. It is further determined that these requirements are in addition to the requirements set forth by the United States Constitution and any law of the United States. (emphasis added)

In addition, there is a link to copies of letters between the South Carolina Democratic Party and the South Carolina Election Commission claiming that the Party is responsible for determining the eligibility of the candidates.

An article on "Vetting Candidates" on the Save Our Rights Wiki contains the responses by 15 states on whose responsibility is it to determine the eligibility of the candidates. In all 15 cases, the relevant state officers have claimed that it is not their responsibility to judge eligilibity of the candidates.

Robert Stevens