Julian Zelizer is a professor of history and public affairs at Princeton University, and author, with Kevin Kruse, of the new book "Fault Lines: A History of the United States Since 1974." The opinions expressed in this commentary are his own. View more opinion articles at CNN.

(CNN) President Donald Trump is threatening to declare a national emergency as a pretext to use Pentagon funding to build a border wall. Democrats should pre-empt Trump by proposing their own solution to end the standoff in Washington.

They should propose a deal that puts the GOP on the spot. Rather than continuing with a debate about whether or not to build a wall, Democrats should shift the debate to different ground: they should propose spending more money to ensure a smarter, more efficient and more humane border policy.

Democrats have already supported this agenda in the existing budget, but by offering to spend more for these measures they can highlight the false choice that the administration is giving voters. Democrats can seize the border issue away from the Republican Party, just as President Barack Obama took the national security advantage away from the GOP in 2008, without accepting their opponent's reactionary outlook on immigration. They can make the spotlight on Senate Majority Leader Mitch McConnell and his fellow GOP senators even brighter, making it even harder for them to keep propping up Trump's presidential chaos.

The notion that Democrats don't care about border security is pure partisan fiction. This is, in fact, one area where there is a rare bipartisan consensus. Much to the chagrin of liberals in his own party, Obama was routinely criticized for being too reliant on deportations as he sought a grand compromise with the Republicans to liberalize immigration laws for those who were already in the country.

Although Democrats in 2019 are more supportive of the humane treatment of people trying to enter at our border, and reject the claim that there is some kind of crisis, mainstream Democrats believe that having a secure border is an essential part of national policy.

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