Ukraine's parliament has refused to consider a conscription bill that proposes a crackdown on draft dodgers.
MPs have criticised certain punishment measures included in the bill as unconstitutional.
Some have also suggested reducing the length of military service proposed in the bill from 36 to 18 months.
The bill was drafted in a bid to conscript more people, as Kyiv faces problems on the battlefield after nearly two years of war with Russia.
It also included plans to lower the age at which men can be conscripted into the armed forces from 27 to 25.
Last month, Ukrainian President Volodymyr Zelensky said 450,000-500,000 extra soldiers were needed to fight Russia's invasion.
But some clauses in the bill have caused outrage, such as limiting draft dodgers' rights to own property and freely use their personal money.
The bill would also allow Ukrainians to be summoned electronically to join the armed forces. At the start of the war, tens of thousands of men volunteered to fight but almost two years on it is getting harder to convince anyone to join up.
In December, Ukrainians living abroad were told they could be asked to report for military service. Defence Minister Rustem Umerov described this as an invitation and the ministry later clarified that it did not imply any sanctions against those who refused to come back.
Mr Zelensky said achieving the increased number of troops was a "sensitive" and costly issue.
This all comes as Kyiv's recent counter-offensive seems to have stalled and provisions of military aid have also taken a knock in recent months. US Republicans blocked a $61bn (€55bn; £48bn) military package and Hungary stopped an EU financial deal worth €50bn ($55bn; £43bn).
White House national security spokesman John Kirby said on Thursday that negotiations over further US assistance had "ground to a halt" as the government continues to negotiate its budget.
Mr Zelensky is currently on a tour of the Baltic states - and is currently in Latvia - to bolster further support including urging Western allies to provide more air defence weapons.
Speaking earlier in Tallinn, Estonia, he warned about the dangers of Western hesitation. He said: "Sometimes the insecurity of partners regarding financial and military aid to Ukraine only increases Russia's courage and strength."
His remarks came as a new US report warned that more than $1bn (£785m) worth of US military aid given to Ukraine since February 2022 was not properly tracked.
The findings by the Pentagon's inspector general said US officials in Washington DC and Europe had failed to properly account for thousands of weapons, including stringer launchers and air defence missiles. It raises concerns that some of the $1.69bn in military aid supplied to Ukraine could have been misappropriated.
But in a letter responding to the report, Col Garrett W Trott of the US military's European Command, emphasised that the report found "no evidence of unauthorised or illicit transfer of EEUM [Enhanced End Use Monitoring] defence articles provided to Ukraine".
And the report itself conceded that it was "beyond the scope" of its inquiry to determine whether any arms had been misappropriated.