It’s now or never for opponents of President Barack Obama’s lawlessness on illegal immigration.

Saying America faces a “perilous hour,” and members of Congress are entering a “momentous week” when it comes to the future of the separation of powers, Sen. Jeff Sessions (R-AL) urged his colleagues on Monday to “be counted” and “stand up” to Obama’s “lawless actions, and sponsor legislation that will block him” from granting amnesty to millions more illegal immigrants.

He also urged colleagues to “oppose any border supplemental that does” not prevent Obama from using federal money to implement more executive actions on immigration. Simply put, Sessions said, there is “no middle ground” when it comes to Obama’s potential nullification of federal immigration laws.

Obama has indicated that he will enact more executive actions and grant work permits–in contravention of federal law–to possibly eight million more illegal immigrants once Congress leaves for its August recess after this week. Sessions has been urging Congress to support bills like Sen. Ted Cruz’s (R-TX) that would prevent Obama from granting temporary amnesty to future illegal immigrants.

“Our response now is of great import,” Sessions said on the Senate floor. “It will define the scope of executive and congressional powers for years to come. If President Obama is not stopped in this action, and he exceeds his powers by attempting to execute such a massive amnesty contrary to law, the moral authority for any immigration henceforth will be eviscerated.”

Saying every member of Congress will face “a time of choosing” this week in which they will be asked to support or oppose legislation that would block Obama’s executive amnesty, Sessions asked, “Will we answer that call? Where will history record each of us stood at this important time?”

“No lawmaker should support any border bill that does not expressly prohibit these planned executive actions by the president and that prohibits any expenditure of funds to implement them,” Sessions said.

He reminded lawmakers in Congress that, “all of us were elected by Americans to serve them and to serve and honor their Constitution,” and Congress’s message to the American people should be clear: “We stand for law, we stand for Constitution, we stand for an honorable, lawful immigration system that treats everyone fairly and serves the national interest of the people of the United States.”

To Sessions, that means marking an end to “this Congress’s acquiescence to executive overreach.” He emphasized that those who refuse to take simple action to stop Obama’s executive amnesty will have voted to enable Obama’s lawlessness.

Sessions said it is a “stark” and “perilous” hour and emphasized that he has never seen “a situation in which a president-weeks in advance-has announced that he’s going to take action that clearly violates law.” Sessions said Obama is taking America into “exceedingly dangerous waters” and a constitutional crisis by “preparing to assume for himself the absolute power to set immigration law in America” with the mentality of, “I’ll just enforce what I wish to enforce” and “determine who may enter and who may work, no matter what the law says, by the millions.”

Sessions said Obama’s actions “would undermine the very sovereignty of the nation” and amount to an “open borders” policy that even the National Journal said would be “explosive.”

“Anyone the world over will get the message: get into America by any method you can, and you will never have to leave,” Sessions said.

He also said Americans “will not accept nullification of their laws passed by their elected representatives,” and that is why “it’s not too late” to stop Obama’s lawlessness.

He also said that recent election results have shown Americans are getting “roused up” because of illegal immigration and “once activated, their power will be felt.” Sessions noted that Americans have been begging Congress for 40 years to enforce its immigration laws, and “they will not sit back and allow Obama to implement through unlawful fiat what they have defeated through the democratic process.”

Sessions said ultimately preventing Obama from enacting more executive amnesty “will be good for the president, really, because it will stop him from taking a step that will mar permanently his presidency and the office of the president.”

He also said he was so passionate about stopping Obama’s lawlessness in order to defend American workers. Sessions declared that Congress can “protect American workers” of all backgrounds, including legal immigrants, by stopping the work authorizations for “those who would then be able to take any job in America at a time of high unemployment” and “falling wages.” Sessions has always made an emphasis to stand up for the American workers and represent their interests in Congress against the so-called “Masters of the Universe.” That has guided his views on unchecked immigration.

He noted that the country’s economy is “not doing well” for many working Americans and simply asked whether more work permits for illegal immigrants would benefit American workers.

“Would it help poor working people all over America? Would it help African-Americans?” Sessions asked. “The experts tell us absolutely not.”

He mentioned that the Congressional Budget Office determined that “if this kind of mass amnesty were to be adopted,” then “wages in America would fall for a decade.”

After also mentioning that the wheels were spinning off the Obama administration’s policies all over the world, Sessions said blocking Obama’s executive actions “will avoid a major government disruption at a time the nation faces many threats” and “protect the rule of law and the constitutional order whereby Congress makes the laws and the president executes them, whether he likes them or not.”

Sessions said the last thing the country needs while it faces so many crises abroad is a “major, internal battle with the president over illegal actions that he’d like to take.”