Actually the media itself should prevent an ineligible candidate from becoming president. Unfortunately their love for Obama wasn’t going to allow them to ask tough questions.
Roger Calero was the socialist party candidate who was on ballots in some states and not others. He isn’t even a citizen.
And if this Calero ever won, someone with standing to sue could take him to court and force him to prove his eligibility. If he couldn’t, he would be kicked out of office. If Obama took a state to court over them not accepting his COLB for ballot eligibility, courts would find the COLB is sufficient.