The most revealing comparison in the July Fairfax Ipsos National Poll is not between Tony Abbott and Bill Shorten, but between both leaders and those who went before them.

Make no mistake. These are the worst set of numbers recorded by a prime minister and leader of the opposition in the recent history of modern polling.

We can debate the attributes where Abbott and Shorten are seen as outperforming each other, but there can be little argument about the central proposition: neither man is cutting it with the electorate.

No indicator better illustrates this than the net approval numbers (approval minus disapproval). For the first time, the prime minister and the alternative prime minister both stand at minus-20 or worse.

This didn't happen when the unpopular Rudd-Gillard-Rudd governments faced an unpopular opposition leader in Abbott. And it didn't happen in earlier times.

If we accept that competence, vision, strength and trustworthiness are the key indicators, both Abbott and Shorten score poorly in all four areas. Let's examine their respective ratings on competence (45 and 52 per cent).

Nine months before he was defeated in the 1996 election, Paul Keating scored 62 for competence against then opposition leader John Howard's 68. Four months before Howard was toppled in 2007, he scored 73 on competence to Kevin Rudd's 74.

"The current levels of approval for party leaders are unprecedentedly low," confirms Ipsos senior project manager Robert McPhedran. "At no point from 1996-2014 have the two party leaders had such low approval ratings. The closest to what we have now was in mid-2012, when Gillard and Abbott both had approval ratings in the mid to high 30s."

Yes, Abbott has improved in a number of attributes since his near political death experience in February – most dramatically when it comes to having the confidence of his party (a 15-point jump to a still modest 56).

But he has gone backwards since the first poll after the well-received May budget. The first post-budget survey gave him a five-point lead over Shorten as preferred prime minister and a disapproval rating of 50 per cent.

Now, despite Shorten recording his worst approval ratings, the Opposition leader is back in front as preferred PM (with a disapproval rating of 55) and Abbott's disapproval is at 59 per cent.

Why so bad? Both leaders are being marked down because faith in the political process as a whole is so low and responsibility for this is a collective effort. But both have also contributed the most recent drop in their ratings.

Abbott's "heads should roll" assault on the national broadcaster may have gone down well with hardliners in his party room, but many in the wider electorate find the resort to brutal sloganeering utterly repugnant. The same goes for his "they're coming after us" rhetoric on national security.

Shorten's poor numbers are the product of a sustained burst of negative publicity, from the ABC's The Killing Season to questions raised about deals done when he was a union leader, and an underwhelming session of parliament.

His appearance at the Royal Commission into union corruption this week has the potential to either compound his problems if he performs badly or improve his standing if he does well.

Monday's summit of Indigenous leaders on constitutional recognition looms as an opportunity for both to show that some issues transcend party politics. Grasp it and voters might have grounds to reassess.