One thing we know at the halfway mark of this campaign is that change is emerging as an overarching theme.

For Fine Gael, the task is to convince voters that change is too risky and puts the economic recovery and the adept handling of Brexit in jeopardy.

For Fianna Fáil, the challenge is to convince voters that it is the only party that can realistically lead an alternative government, the only party that stands a chance of bringing to an end Fine Gael's decade-long hold on power.

For Sinn Féin, the objective is to present itself as the agent of a deeper more fundamental change that can cast off the old-fashioned tribalism of Irish politics and replace it with a something entirely new.

At this stage, it looks like Sinn Féin's brand of change is an easy enough sell.

As she took to the floor of the Claire Byrne Live debate studio in NUI Galway last night, Mary Lou McDonald cast herself as the outsider, the anti-politician figure.

This was not too difficult given the debate started with statements from the leaders of the two biggest parties about why they do not want to do business with them. "Fianna Fáil and Fine Gael have had it all their own way now for almost a century," Ms McDonald said. "The truth is that they don’t want to let the alternative in."

This message was forcefully, if not a little misleadingly, communicated by the Ógra branch of the party, which tweeted a video of what it said was "Mary Lou putting manners on the posh boys".

It is a theme that continued when Sinn Féin launched its manifesto this afternoon. "Do voters want more of the same? Or do they want change that will solve the housing crisis, put money back in people’s pockets, deliver public services and plan for Irish unity," asked Ms McDonald.

The message appears to be resonating. According to the weekend opinion poll by Red C for the Business Post, younger voters in particular are putting their faith in Sinn Féin to solve some of the biggest issues affecting them.

The poll suggests that some 33% of under-35s trust Sinn Féin to solve the housing crisis, compared to 14% who trust Fine Gael and 13% who trust Fianna Fáil.

Recent experience - of both the marriage equality and Repeat the Eighth referendum campaigns - tells us that younger voters are mobilised by issues in a way that they are not by party politics.

If housing is the issue of this generation and if they are motivated enough to vote on that basis in similar numbers as they did in the referendums, then Sinn Féin could could stand to reap the rewards. 

Capturing the mood of change has helped Sinn Féin to have a good election so far. And while the other parties will be careful not to underestimate it (as they did at the start of the campaign) there are questions around whether this momentum can be sustained and whether it can drill down to constituency level.

Their manifesto has just been launched and with their surge in the polls, Sinn Féin is likely to come under far greater scrutiny. Ms McDonald used an interesting phrase when she said her party "would not trespass on the legitimate structures of government".

The party faces questions around what its attitude to certain institutions would be, such as how it would deliver its promise to ensure interest rates are reduced given the independence of the Central Bank.

When you go through constituency by constituency, the surge for Sinn Féin is not as obvious as it is in opinion polls.

There are many areas where it is left with a seriously diminished number of councillors following a poor showing in last year’s local elections.

And there are cases where people who lost their council seats are now seeking to be elected to the Dail - something that would require a huge swing towards the party in a short period of time.

Et Viola!

In other news, the former taoiseach Enda Kenny, who is bowing out of a long political career, is showing signs of having a bit of fun in retirement.

Speaking to the Irishman Abroad podcast, he recounted how US President Donald Trump could not pronounce the name of his wife, Fionnuala, during a St Patrick's Day visit to the White House - "so he called her Viola".

Mr Kenny did not take offence though, telling the podcast: "Now if a row breaks out at home I say: 'Now Viola, calm down a bit!'"