When Dutch voters tune into tonight’s debate — the second in advance of the September 12 parliamentary election — they will be watching closely the man who was deemed to be the winner of last week’s debate.

That’s Diederik Samsom, the leader of the social democratic Partij van de Arbeid (PvdA, the Labour Party), is riding a wave of popularity, with Labour rising very narrowly in the polls and with indications that Dutch voters may be giving Samsom his first real look as they contemplate doubts about Emile Roemer, the popular leader of the Socialistische Partij (SP, the Socialist Party).

A former Greenpeace activist who once studied nuclear energy and physics, Samsom has been a Labour member of the Tweede Kamer, the lower house of the Dutch parliament, since 2003, and has served as the party’s spokesperson for environmental issues.  Hailing from the left branch of the Labour Party, Samsom opposed extending the Dutch military presence in Iraq in 2004 in defiance of much of his own party.

The Labour Party currently holds the second-largest number of seats in the Tweede Kamer — 30 seats to 31 for the party of prime minister Mark Rutte, the the Volkspartij voor Vrijheid en Democratie (VVD, the People’s Party for Freedom and Democracy).

Many Dutch voters appear ready to reject Rutte’s brand of austerity, which would normally leave Labour well-placed for the elections.  Instead, Labour has watched as Roemer and the Socialists bounded to the top of the polls, tied or even leading Rutte’s VVD.

Rutte and Roemer have dominated the fairly laconic campaign so far, with Rutte arguing that the government must reduce its budget deficit to within 3% of GDP by 2013 and Roemer arguing that economic growth is a higher priority.  Roemer, who has mocked the 3% target and the European Union’s influence on Dutch fiscal policy, has nonetheless pledged to bring the deficit to within 3% of GDP by 2015.

That’s roughly the Labour position, too — that the Dutch government should take more time to lower its deficit, and not at the expense of economic growth.  But whereas both Rutte and Roemer have taken a hard line on sending any more Dutch money toward bailing out countries like Greece, Samsom has emphasized that a Greek exit from the eurozone would cause chaos and may, in the long run, cause even more financial harm to the Netherlands.

The fourth party leader in the debate, Geert Wilders of the Partij voor de Vrijheid (PVV, Party for Freedom), who is infamous for his anti-Muslim and anti-immigration views, brought Rutte’s government down in April when his party refused to support further budget cuts and is now arguing that the Netherlands should completely abandon the euro.  Like the PVV and the Socialists, Samsom refused to allow Labour to support Rutte’s proposal last spring for up to €1 billion in cuts, even as other progressive parties, such as the Democraten 66 (Democrats 66) and De Groenen (the Dutch Green Party), begrudgingly supported it.

Rutte’s free-market VVD formed a minority government in 2010 with the center-right Christen-Democratisch Appèl (CDA, Christian Democratic Appeal), with outside support coming from the PVV, until the PVV brought the government down in April.

Samsom became the leader of the Labour Party only in March, when prior leader Job Cohen stepped down after just two years at the helm of the party and Samson defeated Ronald Plasterk and two other opponents.

Cohen, not so long ago, was once the savior of the Dutch — and European — left.

The mayor of Amsterdam from 2001 to 2010, Cohen was touted as a potential, nearly inevitable, prime minister when he assumed the Labour Party leadership in 2010.  Cohen was a Jew whose parents spent World War II in hiding from the Nazis, who nonetheless, in contrast to Wilders, held out a friendly hand to Dutch Muslims.

In his first year as mayor, he was the first government figure in the world to officiate a gay wedding in 2001 after the Dutch same-sex marriage law went into effect.  Later, Cohen guided Amsterdam through the traumatic murder of outspoken anti-Muslim filmmaker Theo van Gogh in 2004, with an emphasis on tolerance, understanding and integrating immigrants into Dutch society.

In opposition to the VVD-led government after Labour won one seat fewer than the VVD in 2010, Cohen veered between attacking the VVD for its dependence on the PVV, and supporting the VVD on those occasions that the PVV refused to back the government.  Cohen watched as the Socialists eclipsed the Labour Party, ignominiously, in poll after poll in the ensuing two years.  Polls showed that Labour would hold just 16 seats when Cohen stepped down as party leader in February.  Today, Labour still seems likely to lose seats, with polls projecting that it will nonetheless hold between 20 and 24 seats — unless Samsom can convince voters to back him as a more sensible alternative to austerity than Roemer’s Socialists.  His election marked a turning point, and his refusal to support Rutte’s budget proposal in April was a key element in the fall of Rutte’s government.

Labour, for its efforts, has underperformed electoral expectations for over a decade:

• After eight years of government under Labour prime minister Wim Kok from 1994 to 2002, the party lost nearly half of its seats in the 2002 elections (going from 45 to 23) under his hand-picked successor, Ad Meklert.
• Wouter Bos assumed the leadership after the failed 2002 elections, and Labour rebounded to 42 seats in the 2003 election a year later, although Bos remained in opposition to the government headed by CDA leader Jan Peter Balkenende.
• Despite expectations that Labour would win the 2006 elections, it fell short again, winning just 33 seats to the CDA’s 41 seats.  After an initial Balkenende government fell in 2007, Labour joined the Balkenende-led government from 2007 to 2010 — Bos served as deputy prime minister and finance minister.
• When Labour pulled out of the government in 2010, after a disagreement over the presence of Dutch troops in Afghanistan, Bos stepped down, paving the way for Cohen’s leadership.

In addition to the four leaders from last week’s debate, CDA leader Sybrand Buma and the leader of the progressive Democraten 66, Alexander Pechtold, will also take part in the debate.