Over the weekend, House Speaker Mike Johnson (R-La.) pronounced that a White House-endorsed border security bill which would also free up foreign aid to Ukraine and Israel would be dead on arrival in the House.

So Monday, President Joe Biden said he’d veto Johnson’s backup plan, a $17.6 billion Israel-only aid package that’s set to be voted on separately this week.

Israel is the United States’ main ally in the Middle East, drawing bipartisan support in Congress. Safeguarding Israel has long been a staple of Democrats’ efforts to maintain Jewish voters as a key political constituency.

But Biden’s threat signaled an effort to turn up the temperature on the border bill fight and may show a newfound willingness to put some daylight between his administration and Israel in the wake of a brutal invasion of Gaza after the Oct. 7 attacks by Hamas.

“The Administration strongly opposes this ploy which does nothing to secure the border, does nothing to help the people of Ukraine defend themselves against [Russian President Vladimir] Putin’s aggression, fails to support the security of American synagogues, mosques and vulnerable places of worship, and denies humanitarian assistance to Palestinian civilians, the majority of whom are women and children,” the White House said in a formal statement.

The White House said it “strongly encourages” both the House and Senate to work on the bipartisan border deal instead.

While such threats often leave a little wiggle room for negotiation, such as saying the president’s advisers would merely recommend a veto, Monday’s statement was a direct veto threat, saying Biden would veto the bill if it passed the House and Senate. Overriding a veto would take a two-thirds vote of each chamber, an unlikely prospect.

The move complicates the already-unwieldy calculus on Capitol Hill as lawmakers try sift through what can gain enough votes to pass and what cannot among competing priorities with varying levels of support in each party: strengthening the border, providing needed military aid to Ukraine and Israel, beefing up Taiwan’s defenses and giving aid to starving Palestinians trapped in Gaza by the invasion.

Republicans had wanted to tie Ukraine aid to border security after jettisoning it in a stopgap funding measure in September. When the Oct. 7 attack by Hamas happened, there was initially talk of twinning Israel and Ukraine aid. Later, the White House agreed to bundle border security; aid to Ukraine, Israel and Taiwan; and eventually humanitarian aid into one bill if agreement could be reached on the border provisions.

But after weeks of drawn-out talks, House Republican leaders balked at the combination bill unveiled Sunday, and several Republican senators gave it a thumbs down, raising the prospect that it may not even make it out of the Senate. Johnson’s announcement that he would have a vote on an Israel-only bill was seen as a move to fend off the larger combination bill.

Polls have shown that aid to Ukraine and to Israel have about equal popularity with the public, but helping Ukraine is far more popular with Democrats while aiding Israel is much more popular with Republicans. The House already passed an Israel aid bill but paired it with Internal Revenue Service cuts that Democrats had objected to, putting the bill on ice in the Senate.

But House Republicans definitely want to be seen as protecting Israel and see an aid package as a part of that.

“Israel needs our immediate support. Any aid package to our greatest strategic ally should be clean, stand alone, and not be slowed down by the politics of other issues,” Rep. Mike Garcia (R-Calif.) posted Monday on social media.