The Department of Home Affairs told the government last week it was aware of 300 cases of people on Manus Island and Nauru likely to be recommended for medical transfer under the new law.
Prime Minister Scott Morrison before losing the vote on Tuesday night.
Attorney-General Christian Porter said up to 300 people on Manus Island and Nauru were within reach of securing the medical approvals required to come to Australia.
"Morrison will be happy to fight an election on this issue".
Morrison last week ruled out calling a snap election if his government was defeated over the "stupid" bill.
Denying that he would try to overrule the vote by blocking it from getting royal assent, Morrison vowed to reverse the "foolish" law should the Coalition be reelected when the polls open in May.
Australia's conservative minority government suffered a damaging political defeat on Tuesday (Feb 12), becoming the first administration in almost a century to lose a vote on major legislation and sparking calls for a snap election. Another lawmaker has since quit the government as part of the bitter fallout over the leadership change.
"Under my government Australia will be stronger".
Earlier, Opposition Leader Bill Shorten sought to send his own message to would- be asylum seekers.
The changes included a provision that only the 1,000 asylum seekers now held on Nauru and Papua New Guinea and not any future arrivals would be considered for medical evacuation under the new regime.
Battered Sexton should be back for Italy trip
Scotland skipper Greig Laidlaw later questioned some of the decisions from French referee Romain Poite. The Scots have won one and lost one so far, having beaten Italy in their opener.
Refugee advocates and lawyers had lobbied senators to back the amendments passed by the House. This has meant that people needing urgent medical assistance have severely deteriorated or even died as a result of delays and political stalling. "Rape survivors have to had to have traumatic late term abortions due to government blocks", she said.
Local council chief executive David Price said the hospital was so small it made more sense to send sick asylum seekers straight to the mainland.
"The government tells us that this bill is a constitutional crisis".
Most refugees who arrived by boat have gone into the community in the past.
The center was completed in 2008 with a capacity of fewer than 2,000 inmates, but by 2013 held nearly 3,000 asylum seekers due to a surge in boats. It was the scene of violent protests, with detainees denouncing harsh conditions. A wooden boat carrying 90 asylum seekers from Iran and Iraq ran onto rocks on Christmas Island in 2010, killing 48.
He declined to specify what those classified measures were, other than to announce the reopening of the camp on Christmas Island, a remote Australian territory some 2,300 km northwest of the western city of Perth.
"The one thing that has not changed is the fact that anyone who gets on a boat today, not one thing has changed for them".
"It should come as no surprise to people that people smugglers have heard what is going on", Mr Dutton said.
Get the Monitor Stories you care about delivered to your inbox.
The UN has criticised Australia's detention policies as "inhumane", but the nation insists they prevent human trafficking and save lives at sea.