With the reopening of the U.S. embassy in Havana, the United States has full diplomatic representation in Cuba for the first time in 54 years. But Congressional Republicans, egged on by their party's presidential aspirants, are trying to cripple the embassy's operations by denying it the money it needs to function effectively—a classic case of cutting off your nose to spite your face.

The Obama administration has requested a $6 million budget increase to expand the embassy's staffing and repair the aging building's dilapidated infrastructure so that it can handle its increased responsibilities.

House Republicans responded by adding an amendment to the State Department's budget appropriation prohibiting any new spending on U.S. facilities in Havana. They would not only deny Obama the funding he requested, but block his ability to reprogram money for the mission even in an emergency. Senate Republicans didn't have the votes in committee to add a similar prohibition to their version of the bill, but will try again when the State Department appropriation reaches the floor.

This amendment is just one of a series that Republicans have added to various appropriations bills in their effort to hobble Obama's opening to Cuba and reinforce the 2016 campaign narrative that Obama is weak on foreign policy. But what about the national interest?

As Assistant Secretary of State for Western Hemisphere Affairs Roberta Jacobson told the House Foreign Affairs Committee, diplomatic relations are not a gift the United States is giving to Cuba. "It's not the Good Housekeeping seal of approval." A normal relationship has practical benefits. U.S. diplomats will have greater access to both Cuban officials and Cuban society. The freedom of our diplomats to travel around the island will mean a qualitative improvement in political and economic reporting compared to what was possible when they were confined to the hot house of Havana. But without the money the administration has requested, these gains will be seriously limited.

Crippling the embassy financially does nothing to hurt the Cuban government. The only people hurt will be the U.S. diplomats forced to work in a substandard facility with inadequate staffing; the tens of thousands of Cubans seeking visas to come to the United States; and the U.S. citizens and residents traveling in Cuba who need consular assistance.

Before the U.S. mission became a full-fledged embassy, the size of the U.S. staff was limited to 51 diplomats by 1977 agreement with Cuba that established the "Interests Sections." That level of staffing has long been inadequate, as a May 2014 report by the State Department Inspector General noted. The Republican spending limit would prevent the department from increasing it even though the work load for our representatives is growing rapidly.

The need for physical repairs at the embassy is even more pressing. The last major renovation took place in 1997. The 2014 Inspector General's report warned that the half-century old building along Havana's seaside boulevard, the Malecón, is exposed to "high winds and salt air" and in need of constant repair. The consular annex was judged to be structurally unsound.

Every year, the consular section processes visa requests from over 50,000 Cubans seeking to travel to the United States either as immigrants or visitors. That volume has increased substantially in the three years since the Cuban government liberalized travel regulations. At the same time, the number of U.S. citizens and residences traveling to Cuba topped half a million in 2014, and interest has exploded, up 36 percent since Obama's December 17 announcement on normalizing relations.

The Republican spending limit would prevent the State Department from expanding the consular staff to handle the rapidly growing demand for services or upgrading their facility so that they have a decent place to work.

Cuba is not an easy place to operate for a U.S. diplomat; the State Department euphemistically calls it a "restricted environment." Serving in a country we have regarded—and that has regarded us—as the enemy for half a century poses tough challenges. As diplomatic ties are restored and relations thaw, some of those challenges will ease. Now is not the time for partisan politics at home to put a straightjacket on our diplomats abroad, preventing them from taking advantage of the new opportunities full diplomatic relations provide. As Congress considers funding for the embassy in Havana, it should keep in mind its responsibility to those officers and to all the people they service—Cubans and Americans alike—not to make their job any harder than it is already.

LeoGrande is professor of Government in the School of Public Affairs at American University and coauthor with Peter Kornbluh of Back Channel to Cuba: The Hidden History of Negotiations between Washington and Havana.