Ley leaves Taylor an immediate electoral test with Farrer by-election

Within two hours of being elected Liberal leader, Angus Taylor has already been delivered his first big electoral test, and it has come from the woman he deposed.

Former Liberal leader Sussan Ley has declared she will also soon be the former member for Farrer.

She intends to resign in coming weeks, sparking a by-election in her massive western New South Wales electorate.

It could be a very interesting and complicated election.

Having served a few weeks longer than Alexander Downer did in 1994-95, and a couple of weeks less than Brendan Nelson after the defeat of the Howard government in 2007, Ley's leadership is the second-shortest of any federal Liberal leader.

But her tenure as the member for Farrer is the second-longest in the seat's history.

The seat was held by former deputy prime minister Tim Fischer, a National, until his retirement in 2001.

Both Coalition parties contested the 2001 election, and Ley easily topped the primary vote. Labor preferences favoured the Nationals, which narrowed her victory after preferences to a margin of just 206 votes.

Coalition rules prevent members challenging sitting MPs of the other party, so Ley has held the seat relatively comfortably since then.

Both Coalition partners will be interested in Farrer

Farrer overlaps with two state electorates. There's Albury, dominated by the regional centre of the same name and held by the Liberal Party.

The other state seat is Murray, which is currently held by an independent, but has a long Nationals history.

The region also holds deep history in conservative politics: Albury was the site of one of Robert Menzies's conferences of conservative parties in 1944 that eventually led to the formation of the Liberal Party.

With the seat about to become vacant, both Coalition partners will be able to contest it as they did in 2001.

Presumably both will and the by-election risks reopening some wounds between the parties that have only just been bandaged up.

After once again renegotiating a new Coalition agreement, Angus Taylor and David Littleproud would need to be besties while at Parliament House and then drive 200 kilometres down the road to campaign against each other.

And that's before we consider the other players that are likely to throw their hat in the ring, such as One Nation.

Potential for a bigger contest

We can probably expect to see at least one independent candidate put their hand up. Independent Michelle Milthorpe polled 20 per cent in last year's election and finished second in the seat after preferences.

Could this become a complicated three- or even four-way contest?

Prospective candidates have a bit of time to get their ducks in order and build support, given Ley is not resigning immediately.

Depending on when she hands her resignation to Speaker Milton Dick, we wouldn't expect polling day until at least late April.

After nearly a quarter of a century in federal parliament, Ley, with no real prospects of returning to leadership, has made the decision to leave.

She says she's leaving parliament to give the new team "clear air", something she says "is not always afforded to leaders".

It is easier for a new leader to get that clear air without their predecessor breathing down their neck.

In the short term, however, her decision to leave creates an immediate challenge for her successor.

It will no doubt bring Taylor's leadership into sharp focus and be a distraction for both Coalition parties, which continue to say they would rather be holding the Labor government to account.