The first issue is environmental taxation, which forms the centrepiece of the new economic policy adopted at last year's Conference in Brighton. Chris Huhne supported this strongly during the leadership election, but Ming was far less convinced - as I pointed out at the time.
The second issue was the setting of a deadline for the withdrawal of British troops from Iraq. This was the subject of a clash between Huhne and Campbell during the special Question Time programme that the BBC organised during the campaign. As its website reported:
Perhaps this is not such a surprise. Ming Campbell's appeal to the party and to the voters has never relied strongly upon his command of policy detail. It has always relied more upon his personal qualities - particularly gravitas (or "bottom", as they used to say in the 18th century). Such ideas as there were during the leadership campaign came largely from the Huhne camp.
The Lib Dem leadership challengers have clashed over when British troops should be pulled out of Iraq.
In a BBC Question Time debate, Simon Hughes and Chris Huhne pushed for troops to leave by the end of 2006.
Mr Huhne said he knew from his time in business that deadlines were the best way of ensuring things happened.
But Sir Menzies Campbell, who does not want to set a firm deadline, countered, saying: "There are 8,500 lives at stake. This ain't business."
But issue 309 of Liberator magazine (.pdf file downloadable from here) gives another clue to what was going on. The magazine's Radical Bulletin section wrote:
Yes, there was an element of calculation to the Huhne campaign. But I suggest the issues that would help the third candidate in a Lib Dem leadership election have a lot in common with those that would help the third party in a general election.
But how was Huhne to carve out a platform distinct from his rivals? Those present at the leadership hustings in East Grinstead found out when Lord Oakeshott, appearing on Huhne's behalf, for some reason chose to announce his campaign secrets from the platform.
He said a group of backers had looked for "wedge issues" that would get the relatively unknown Huhne noticed. They lighted on withdrawing troops from Iraq, not renewing Trident and a greater environmental emphasis as areas on which they could challenge Campbell and, presumably, win some supporters over from Hughes.
Oakeshott did not say that these issues were particularly dear to Huhne, merely that they were chosen from their ability to attract attention.
Which is why the Huhne line has become the Lib Dem line on two of the three issues he identified.