Prime Minister accused the IMF of coming up with "new demands for Greece; absurd, imaginary unreal."
The reforms are necessary to secure further bailout funds from Greece's creditors.
The bill lawmakers will vote on late on Wednesday covers rules for dealing with failed banks and speeding up the justice system.
After an initial wave of selling, European stocks and the euro recovered some ground.
Tsipras asked Juncker to help get the program "extended by a few days and help restore the Greek banking system's liquidity."
Greek prime minister shakes up negotiating team and takes controversial finance minister, Yanis Varoufakis, out of the limelight.
Experts say that the last minute clamp down is too little too late.
Angela Merkel says Grexit must be prevented while Varoufakis writes that disagreements with creditors are "not unbridgeable".
The environment minister has revoked a license leaving gold stuck in a mine in northern Greece.
Finance minister pledges to "reform Greece deeply" as deadline for €450 million loan repayment to IMF approaches.
Visit will focus on lifting Russian embargo on Greek products and improving energy cooperation.