The governor of Oregon says she'll resist any attempt by Donald Trump to deploy her state's National Guard detachment to protect America's southern border, and California's governor appears poised to follow suit.

The president signed a proclamation on Wednesday that orders Defense Secretary James Mattis to 'request use of National Guard personnel to assist' with the Homeland Security Department's existing border patrol operations.

But governors, whose duties include commanding their states' Guard units, can say no.

'If @realDonaldTrump asks me to deploy Oregon Guard troops to the Mexico border, I'll say no,' Oregon Gov. Kate Brown tweeted Wednesday. 'As Commander of Oregon's Guard, I’m deeply troubled by Trump’s plan to militarize our border.'

Oregon is about 1,000 miles from where the U.S. ends and Mexico begins.

Kate Brown, the Democratic governor of Oregon, said Wednesday that she'll refuse to comply with any Trump administration request for National Guard troops to patrol the nation's southern border

President George W. Bush deployed National Guard troops to the Mexican border with assistance from the four border states in 2006

Oregon Gov. Kate Brown says she'll refuse any request for the use of her state's troops – even though her state is 1,000 miles away from where the U.S. ends and Mexico begins

Brown acknowledged in a second posting that '[t]here's been no outreach by the President or federal officials,' but insisted that she has 'no intention of allowing Oregon's guard troops to be used to distract from his troubles in Washington.'

Presidents can call up National Guard units using two different legal authorities, both enacted by Congress in 1956.

One, known as Title 10, would allow Trump to 'federalize' the Guard, ordering it to assemble for 'active duty.' That is typically reserved for wartime deployment or an officially declared 'state of emergency. It also would apply if there were an open rebellion against the government.

But Trump invoked the weaker Title 32 law, which puts the burden on governors to order the Guard to duty 'for operational Homeland Defense activities,' according to a the National Guard Association of the U.S.

That means Oregon's governor and others can ignore the president's order entirely – or refuse it publicly.

Texas Gov. Greg Abbott, a Republican, said Wednesday that he welcomes the National Guard order from Washington, and noted that 'Texas has maintained a continuous presence of National Guard members along the border' since he took office.

Oregon is nowhere near Mexico. But like Texas, California is – and Golden State governor Jerry Brown is the only Democrat serving as chief executive of a state that shares America's southern border.

President Trump used the weaker of two statutes available for National Guard call-up, meaning governors can refuse to participate

Far from home: In this June 20, 2008 photo, members of the 200th Red Horse Air National Guard Civil Engineering Squadron from Camp Perry in Ohio worked on building a road at the border in Nogales, Arizona

His buy-in is unlikely, even though California supported previous National Guard border operations – including George W. Bush's deployment of 6,000 troops in 2006 and Barack Obama's use of 1,200 four years later.

Homeland Security Secretary Kirstjen Nielsen said Thursday on the Fox news Channel that she isn't giving up on him.

'We sent him some information with respect to our best advice as how we could use the Guard to support our mission,' she said.

Nielsen suggested that she wants troops to patrol borders near where they live.

'The men and women on the front lines if you will, whether they be state employees or federal employees, they usually have much better grasp of what we need,' she said.

Nielsen also seemed to concede that some cajoling and arm-twisting will be necessary in order to execute on Trump's order – and that Jerry Brown is entitled to decline.

'I'd would like further conversations with him,' she said, 'before I jump ahead of him and how he would like to secure his border.'

Homeland Security Secretary Kirstjen Nielsen said Thursday that she's going to try to get California Gov. Jerry Brown to help, even though he's an anti-Trump liberal Democrat

White House Deputy Press Secretary Hogan Gidley said the administration isn't putting a number on the troop deployment, only specifying that it would be 'whatever it takes'

White House Deputy Press Secretary Hogan Gidley said on the same network, two hours later, that '[w]e hope all governors would participate in helping to make America a much safer place.'

Asked how many Guard troops the Trump administration would put on the border, he replied: 'As many as it takes.'

In Obama's border deployment, Guard troops were limited to advisory and observer roles, serving as extra eyes and ears for U.S. Border Patrol units and often limited to using binoculars in guard towers.

Under rules of engagement issued by Obama's Pentagon, they were forbidden to pursue, confront or detain suspects, including illegal immigrants.

They also couldn't make arrests, stop or search vehicles, or seize drugs.

Trump's Defense Department hasn't said what Guard troops will be told this time around, but the president's proclamation specifies that their mission would be 'to stop the flow of deadly drugs and other contraband, gang members and other criminals, and illegal aliens into this country.'