Twelve Republican senators sided with Democrats Thursday and voted to block President Donald Trump's declaration of an emergency on the southwest border. Trump has vowed to veto the Democratic measure, which the House passed last month in a bid to stymie Trump's efforts to spend billions of extra dollars on a U.S.-Mexico border wall.

Of the dozen GOP senators who went against Trump, just one — Maine Sen. Susan Collins — faces re-election next year.

A look at what the Republican defectors said about their votes:

— Lamar Alexander of Tennessee: "After a Revolutionary War against a king, our nation's founders gave to Congress the power to approve all spending so that the president would not have too much power. This check on the executive is a crucial source of our freedom."

— Roy Blunt of Missouri, a member of the GOP leadership: "I was aggressively opposed to the Obama administration's attempts to circumvent Congress's appropriating authority to prop up" the health-care law known as Obamacare. "The same principle should apply regardless of which party occupies the White House."

— Collins: "I'm sure (the president) will not be happy with my vote, but I'm a United States senator and feel my job is to stand up for the Constitution. So let the chips fall where they may."

— Mike Lee of Utah: "Congress is supposed to be the first among the federal government's three co-equal branches. For decades, Congress has been giving far too much legislative power to the executive branch."

— Jerry Moran of Kansas: "I aggressively opposed the overreach of past presidents and believe that I cannot pick and choose to now look the other way. How we do things — even good things — matter. We were raised that the ends don't justify the means."

— Lisa Murkowski of Alaska: "When the executive branch goes around the express intention of Congress on matters within its jurisdiction, we must speak up or legislative acquiescence will erode our constitutional authority."

— Rand Paul of Kentucky: "I stand with President Trump on the need for a border wall and stronger border security, but the Constitution clearly states that money cannot be spent unless Congress has passed a law to do so."

— Rob Portman of Ohio: "There is no question we need stronger border security. Erecting more barriers and fencing in key areas along the border will help stem the tide. But we have to do that in the right way. Congress, not the president, has sole authority to determine how to spend taxpayer money. Declaring a national emergency to access different funds sets a dangerous new precedent."

— Mitt Romney of Utah: "This is a vote for the Constitution and for the balance of powers that is at its core. For the executive branch to override a law passed by Congress would make it the ultimate power rather than a balancing power. I am seriously concerned that overreach by the executive branch is an invitation to further expansion and abuse by future presidents."

— Marco Rubio of Florida: "We have an emergency at our border, which is why I support the president's use of forfeiture funds and counter-drug money to build a wall. However, I cannot support moving funds that Congress explicitly appropriated for construction and upgrades of our military bases. This would create a precedent a future president may abuse to jumpstart programs like the Green New Deal" or other liberal ideas.

— Pat Toomey of Pennsylvania: "I support what the president is trying to do. I don't support the way the president is going about it, and to me that's an important distinction." Trump's emergency declaration "set a troubling precedent" regarding the president's ability to go around Congress and redirect tax dollars for other purposes, Toomey said.

— Roger Wicker of Mississippi: "I strongly support (Trump's) plan to build walls on our southern border, but an emergency declaration (is) the wrong approach. The president already has almost $6 billion available that can be used to build border walls. I am concerned about the precedent an emergency declaration sets, which might empower a future liberal president to declare emergencies to enact gun control, address 'climate emergencies' or even tear down the wall we are building today."