Did voters express their concern about government control of the Senate when they voted last month? The evidence is difficult to interpret but the result is clear: the Coalition is better placed than Labor to throw its weight around in the upper house.

According to Australian Social Attitudes 2, published in October this year, 57% of voters considered the Coalition government’s control of the Senate “a bad thing“. The figure comes from a survey carried out in late 2005 and early 2006, not long after the Coalition took control of the Senate on 1 July 2005.

To get an idea of whether this attitude reflected the Coalition’s behaviour since mid-2005 or was more longstanding, the editors of Australian Social Attitudes 2 looked at the results of a longer running survey, the Australian Election Study, which has asked respondents after every election since 1993 whether they prefer “divided control” of the House of Reps and the Senate.

The AES figures show a jump in support for divided control between 2001 and 2004. Not surprisingly, it’s almost entirely accounted for by the jump in support among Labor voters, from 50% to 74%. But nearly a third of Liberal voters have consistently said they oppose government control of the Senate after every election since John Howard became prime minister.

Because these surveys are carried by mail they probably overstate the level of opposition to a government-controlled Senate. Yet it’s clear that a significant proportion of voters – perhaps half – are wary of a government controlling both houses of parliament.

The problem for the individual voter is deciding what he or she can do to help avoid that situation. A Liberal voter, for example, breakfasting on 24 November this year, might have made the judgement that Labor was bound to win the day’s election. Or she might have been influenced by the late polls (or the not-so-late commentators) suggesting the Coalition could scrape back in.

How to vote in the Senate then? If Labor was going to win, a vote for the Liberals seems prudent and loyal. If the Coalition looked like winning, then Labor or the Greens might be the best bet, even if it goes against the grain. But what if the polls – whichever way you interpret them – are wrong?

If the breakfasting voter was a Labor supporter then the choices were equally difficult.

This gives a clue as to why – even now that the Senate count is nearly complete – it’s difficult to assess the extent to which those 50% of the electorate might have acted on their belief in divided control. The problem is further complicated by the fact that a group of Labor voters routinely votes differently in the Senate – for the Greens or, going back an election or two, for the Democrats – while half expecting their vote to end up benefiting Labor.

What the Australian Electoral Commission’s Senate figures do show is that the Coalition primary vote in the Senate was 5% lower than the vote in the Reps – an increase over the 2% gap that’s prevailed (by my calculation) at the previous two elections.

After adjusting for the extra number of votes overall, that 3% shift translates into an extra 63,501 votes cast by lower house Coalition voters for other parties in the Senate. Put another way, the Coalition’s adjusted primary vote fell by 571,144 in the Reps and by 634,645 in the Senate. It’s not a big shift – around 1.2% of the overall Coalition vote – but not negligible either. It’s impossible to say, though, what motivated those voters to split their vote.

So, the figures are inconclusive. But the overall result is clear, and it’s in line with what respondents told the editors of Australian Social Attitudes 2. Labor won’t control the new Senate; it will need the support of all non-Coalition small-party senators to get its legislation through. The Coalition, on the other hand, will only need to persuade Family First’s Steve Fielding to help it block government legislation.