Bid officials said they were in the last stages of compiling the file, with the national, regional and local governments discussing the final guarantees.
Final approval is due in the next week although reports in Poznan suggested that the bid was on the verge of collapse because city politicians will not guarantee the financial outlay needed to stage the games.
This was disputed by Grobelny who said there is a common will for Poznan to stage the Youth Olympics - it lost out to Nanjing in China in the contest for the 2014 edition - and that discussions over guarantees were "normal procedure."
Grobelny told Sportcal: "The Poznan City Council and the Polish national government are totally committed to bidding for and staging the 2018 Youth Olympic Games. The financial guarantees are currently being discussed among the local, regional and national governments and will be presented with the final candidature bid file.
"Poznan put forward a strong bid for the 2014 YOG and with our bid for the 2018 YOG we want to once again show our commitment to the Olympic Movement."
The city would need to provide around 77 million zlotys ($24 million), or 24 per cent of the total budget of the games if Poznan is selected as the host in 2018. The remainder would come from the regional Wielkopolska government and the central government.
The IOC will not entertain a city's bid for an Olympic Games unless all financial guarantees are in place.
Around 130,000 zlotys has already been spent on the candidature file, which must be presented to the IOC in Lausanne by October 15.
Within Poznan, the bid is backed by the Grobelny Poznan Civic Movement, representing the mayor's office and which has eight votes when it comes to deciding on policy. The Democratic Left Alliance and Law and Justice, the second of which is one of two major political parties in Poland, have a combined 12 votes and are opposed to the Youth Olympics bid because of the costs involved.
They argue that, having spent money to ensure Poznan could host three group stage matches at soccer's Euro 2012 European Championships, co-hosted by Poland and Ukraine, now is the time to improve the city's financial situation, not continue spending on sporting events.
The balance of power lies with Civil Platform, the other major political party in Poland, which has 17 votes in the Poznan city government and is believed to support the Youth Olympics bid.
The city faces competition from Medellin (Colombia), Buenos Aires (Argentina), Guadalajara (Mexico), Rotterdam (Netherlands) and Glasgow (Scotland) to stage the 2018 games.
The IOC executive board will draw up a shortlist in February 2013, after which an IOC Working Group will publish a report on the candidates.
IOC members will select the host city at their meeting in Lausanne on July 4.