If  John McCain had done something like this, it would be front page news and doom his candidacy:

From Hot Air:

According to internal Soviet Union documents from the SALT-2 negotiations in 1979, Joe Biden effectively told Soviet negotiators not to worry about American rhetoric about human-rights concerns.  In fact, Biden also told the Soviets that the Senate didn't really care about European security, but only in giving the appearance of caring about it.  Vladimir Bukovsky and Pavel Stroilov parse the dispatch from the deputy head of the International Department of the Communist Party of the Soviet Union for Front Page Magazine.

The delegation did not officially raise the issue of human rights during the negotiations. Biden said they did not want ‘to spoil the atmosphere with problems which are bound to cause distrust in our relations.' However, during the breaks between the sessions the senators passed to us several letters concerning these or those ‘refuseniks'. ...

Unofficially, Biden and [Senator Richard] Lugar said that, in the end of the day, they were not so much concerned with having a problem of this or that citizen solved as with showing to the American public that they do care for ‘human rights'. They must prove to their voters that they are ‘effective in fulfilling their wishes'. In other words, the collocutors directly admitted that what is happening is a kind of a show, that they absolutely do not care for the fate of most so-called dissidents.

In the same conversation, Biden asked us to ensure that senators' appeals on those issues are not left unanswered - even if we just reply that the letter is received but we cannot do anything.

If Biden sold out the refuseniks while he and his party screeched about their plight, then he has already demonstrated a lack of resolve and character for higher office. Biden needs to explain himself.