Story highlights Members of parties appear skeptical that Mexico will pay for a border wall

With 52 Republicans, the party would need eight Democratic senators to break a filibuster

(CNN) Senior Democrats privately say that a funding bill to build the border wall will likely be blocked in the Senate -- especially if the plan would add to the deficit or impose a new tax on Mexican imports.

The threat, voiced by multiple sources, marks the clearest indication yet that President Donald Trump might not get Congress to foot the bill for the wall, imperiling his central goal that he made a centerpiece for his campaign.

Trump and GOP leaders have discussed advancing a new funding package that could cost upwards of $15 billion to pay for the wall -- as the new president has promised that Mexico will ultimately reimburse the United States for the project.

But many in both parties are skeptical that Mexico will pay for the wall as the country has insisted that it would not foot the bill. And it's unclear how Trump's funding package will be paid for or if it would be offset by new spending cuts.

With 52 Republicans, the party would need eight Democratic senators to break a likely filibuster. Democratic sources are already confident that most, if not, all of their members will join forces to try to block the plan. Even some fiscal conservative Republicans may balk at the price tag.

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