Ambition was the underlying theme of Jo Swinson’s first speech as Liberal Democrat leader. Literally in her references to the party’s history and to the ambition and determination needed to imagine a “better future” — the theme she returned to in her closing lines — but also tactically: this is a speech that continues the party’s ambitious strategy to use Brexit to leverage a broader realignment of politics, away from left vs right and towards liberal cosmopolitanism versus authoritarian conservativism.

As with so many of Swinson’s moves this week, the speech was all about finding ways to scream “We’re open!” — in one case, literally — at socially liberal voters, and to paint her political opponents, Boris Johnson, Jeremy Corbyn and Nigel Farage as one and the same. That’s part of why the party has backed the revocation of Article 50 – in the highly unlikely event of a Liberal Democrat parliamentary majority — and it underlined every applause line and every policy that she promoted in the speech.

Will it work? It’s worth remembering when we assess the Liberal Democrats that, unlike Johnson and Corbyn, both of whom are incredibly well known, both the party and its new leader have a much lower profile. At the start of the year, just four voters in ten knew what the party’s position was on Brexit and it is still just six in ten now. As far as the Liberal Democrats’s interest goes, the louder they are the better. They need to talk big even to make a small impact — let alone to get close to equalling the scale of the professed ambition in this speech.

The party does genuinely believe that the Remain/Leave divide — and the broader global shift in advanced democracies from traditional drivers of political division — are an opportunity for them to become a genuine third force in British politics, and that striking polarising positions on that and other liberal issues is the way to make it big. But their ambitious talk is also a defensive tactic as well as an offensive one.

Usually, the Liberal Democrats tend to enjoy electoral success when their target voters are turned off by one of the parties. From the mid-1990s through to the Iraq War they did best by providing a home for disgruntled Conservatives who were relaxed enough about Tony Blair to see a Liberal Democrat vote as a risk-free proposition. In 2005, when there was no realistic prospect of Michael Howard becoming prime minister, the Lib Dems were able to act as a home for Labour voters disgusted at the Iraq war.

The party has tended to be squeezed when the result is up for grabs — as they were in 2010, when they lost seats on 2005 — and the problem may be still more acute at the next election. Their strategic advantage — that many voters dislike both Boris Johnson and Jeremy Corbyn — carries with it a big vulnerability – that very few voters dislike the two men equally and may opt for the one they loathe less to keep out the other.

Bluntly, talking up their ambition is the only way for the Liberal Democrats to get out of that hump — it’s basically all about reassuring those voters that it doesn’t matter, because a vote for the Liberal Democrats is a vote to escape both parties by realigning politics. Swinson needs voters to believe that she is serious about changing politics even to have a chance of getting back to the party’s pre-coalition parliamentary peak, let alone to actually pull off the realignment the Lib Dems craves.

Will loudly talking up how open and ambitious they are convince enough voters for it to work? Perhaps – but Liberal Democrats will be reassured that Swinson proved this week that she knows how to locate the foghorn.