Polls put the VVD and PvdA at around 35 seats in the 150-seat parliament, indicating a coalition involving both parties may be inevitable.
Rutte and Samsom have both said that it will be difficult for them to work together after the election, but other parties have indicated that the two leaders have already made a pact.
"We have not made an agreement and there are lots of other options in which we would not have to be in a cabinet with each other," Samsom said during a TV-debate with Rutte Monday night.
Rutte likewise called the suggestions of a deal "complete rubbish".
Samsom and Rutte have found common ground on issues from the euro to international affairs, but they are also divided over immigration, welfare and the housing market.
In the runup to the election day, TV-debates have focused on the economy, EU relations, the euro and health care.
In the televised debates, Rutte stated that "enough is enough" when it comes to Greece and a third bailout. Samsom, on the other hand, emphasised that Greece might need more time and money to make the reforms work.
The live election debates on Dutch TV have pulled in more than one million viewers each time, ranking them among the most watched programmes lately.
Dutch voters in doubt
A day before the election, 27% of Dutch voters said they were still undecided, making a surprise result a possibility.
One such undecided voter, 25-year-old sales representative Rosalie Koerts, said the election was "about getting the nation out of this economic mess we have created". At the moment, four to five parties could still potentially get her vote and she is using an online tool to compare their views.
Another Dutch voter, Paul Mulder, who works at Keesing, said that despite the extensive focus on the political campaigns, he was not satisfied with the way Dutch media had covered the election. He was particularly unhappy with the TV-debates.
"The shows all look for one-liners, fierce and short debates, and break points, leaving very little time for depth and details," Mulder told EurActiv.
He said he would vote for a party that would have solutions regarding Dutch and European economic growth, EU integration, financial shortages and how to tackle national issues, such as the housing market, education, environment and health care.
Since the Second World War, it can take more than three months to form a Dutch government. This doesn't mean, however, that the country is unable to move forward, one analyst said.
"Foreign press always thinks that the Netherlands needs a government to take steps on an EU level," Hans Vollaard, assistant professor at the Institute of Political Science at Leiden University, told EurActiv.
"Of course a new government can do that more easily, but particularly the last two years have shown that coalition parties can conclude deals particularly on EU issues so there is a kind of flexibility on EU issues in the Dutch parliament," Vollaard said.