Angus Taylor's new immigration policy matters not just because of what it proposes, but because of what it signals. This is the first major ideological marker of his leadership, and he has chosen to plant it on terrain long seen as politically potent and dangerous: immigration, national identity and social cohesion.

The opposition leader will unveil the details this evening in a speech to the Menzies Research Centre, but based on what we know so far the package includes expanded social media screening of visa applicants, a new values-based compliance framework, a 'safe country' list for some asylum claims, tougher action against overstayers and a return to temporary protection visas.

That makes this more than just another opposition announcement that comes and goes. It is an attempt to redraw the immigration argument. 

Taylor is plainly trying to position the Coalition as the party willing to say that migration is not just about economics, but also about cultural fit. In doing so, he is moving into territory that Liberal leaders have usually approached with caution, especially at the federal level.

Historically, the obvious comparison is John Howard in 1988. 

Howard then called for a slower rate of Asian immigration, triggering a backlash inside and outside of the Liberal Party. 

Philip Ruddock later recalled crossing the floor on the issue, and Howard has since acknowledged that his stance on immigration helped cost him the leadership in 1989.

Taylor is testing a similar proposition, albeit in a different form, he hopes won't be shot down: that there is political reward in being more selective, more sceptical and more explicit about who fits and who does not.

The difference is that Taylor is trying to build his case around 'Australian values' rather than race. The argument is that migrants from liberal democracies are more likely to align with the norms of a liberal democracy like ours than migrants from authoritarian states or illiberal political cultures.

That is a more defensible proposition in public debate than crude ethnic preferences, and Taylor knows it. He is trying to construct a cultural and political hierarchy rather than a racial one. But that does not remove the controversy. It merely relocates it. And what about the economic consequences of curtailing immigration of almost any sort?

Once a major party says immigration should be filtered through a values test, a series of hard questions immediately follows. Who defines those values? 

How are they measured? Who applies the test? What does alignment actually mean in practice? Is it about attitudes to democracy, women, free speech and secular law? Or is it a looser proxy for country of origin, religion and worldview?

And if social media vetting becomes part of the machinery, how wide is the net cast and how subjective do those judgments become?

A policy minefield awaits the details, which is not to suggest it won't be popular.

Large parts of mainstream Australia are plainly more anxious about immigration than elite commentary often admits. Cost of living pressures, housing scarcity, strained infrastructure and broader unease about social fragmentation have changed the politics of migration substantially in recent years.

Polling and public debate have moved well beyond the old bipartisan comfort zone that assumed high migration was politically easy so long as it was framed as economically necessary. Taylor is trying to meet that shift head-on, and in a sense the politics of the move are easy to understand.

It may also work, at least in part. A policy that links migration to national cohesion, border integrity and pressure on housing will resonate in outer suburban, regional and working class seats where the Coalition has been leaking support to One Nation.

Taylor is trying to tell those voters that he sees what they see and is prepared to act on it. That is the point of the exercise. It's also why this policy was already well on its way to being released when Sussan Ley was still leader. Her team was trying to find a way of thwarting the rise of Pauline Hanson.

But there is an obvious strategic trade-off here. The harder Taylor leans into this territory, the harder he may make it for the Liberals to recover in teal-held metropolitan electorates. His shadow treasurer, Tim Wilson, might struggle to retain his seat once held by the teals.

Those seats were already difficult enough for a party squeezed between inner-city moderates on one side and populist discontent on the other. A values-based migration policy may help steady the drift to One Nation, but it is unlikely to make affluent urban moderates feel that the modern Liberal Party is returning to them. 

Far from it.

That is the larger dilemma. The Liberal Party is no longer fighting on one front. It is trying to hold together voters who are drifting away from it for very different reasons. In that sense, Taylor's announcement is not just an immigration policy. It is a declaration about which side of that internal contest he thinks matters the most right now. He's going after voters drifting to One Nation; he'll worry about the teals later on.

There is another risk as well. If the policy ends up looking more symbolic than operational, it won't strengthen Taylor; it will expose him. 

Values language can sound muscular in a speech, but unless it is anchored in workable law and administratively defensible rules, it can quickly look like politics masquerading as policy. And because this area touches on liberal democratic principles as well as border control, the standard of proof ought to be high.

Still, whatever one thinks of this policy set to be formally announced this evening, it should not be dismissed as fringe or theatrical. It is neither. It is a calculated response to a real shift in public sentiment, and to a real electoral threat from the right that Australia's mainstream conservative party can't just ignore. 

The deeper question is whether Taylor can prosecute his argument without reducing it to a coded form of discrimination, and whether the Coalition can gain on one flank without further alienating the other.

That is the gamble he is choosing to take with his first foray into serious policy as the new opposition leader. Ironically, perhaps, he is doing so by simply dressing up a policy his predecessor was already working on.