Here's an interesting, official account of the arguments over the possible impeachment of Spiro Agnew. Money quote:
Nixon had quipped that Agnew was his insurance against impeachment, arguing that no one wanted to remove him if it meant elevating Agnew to the presidency. The joke took on reality when Agnew asked House Speaker Carl Albert to request that the House conduct a full inquiry into the charges against him. Agnew reasoned that a vice president could be impeached but not indicted. That line of reasoning, however, also jeopardized the president. For over a century since the failed impeachment of President Andrew Johnson, it had been commonly accepted reasoning that impeachment was an impractical and inappropriate congressional tool against the presidency. Agnew's impeachment would set a precedent that could be turned against Nixon.
A brief from the solicitor general argued that, while the president was immune from indictment, the vice president was not, since his conviction would not disrupt the workings of the executive branch. Agnew, a proud man filled with moral indignation, reacted to these arguments by digging in his heels and taking a stance that journalists described as "aggressively defensive."
Sounds like Cheney, no?