Congress has had difficulty accomplishing much in this session, even where a potential health crisis like the Zika virus is concerned. Here are five questions that help explain the debate.

What are they fighting over: money or politics?

Ask Democrats, ask Republicans, and they will tell you the same thing: It’s politics — specifically, Planned Parenthood. Republicans inserted new limits on Planned Parenthood into the latest $1.1 billion proposal to fight the mosquito-borne Zika virus, which can also be transmitted sexually. The bill would exclude Planned Parenthood from the list of providers that receive new funding for contraception to combat the spread of the virus.

Both sides accuse each other of blocking much-needed money for women and children in a public health crisis. Democrats regard any restriction on Planned Parenthood as a deliberate Republican effort to doom the bill. Republicans argue that such limits will not hinder efforts to curtail the virus.

How close is the government to running out of money to fight Zika, anyway?

Too close, according to the Centers for Disease Control and Prevention. Last week, the head of the agency, Dr. Thomas R. Frieden, told reporters the C.D.C. had spent $194 million of the $222 million allocated to fight Zika.

About $35 million of that has gone to Florida, where it has mostly been devoted to killing mosquitoes, and that money has been rapidly running out.

Isn’t mosquito season over? Are there signs that Zika is spreading beyond Florida?

Labor Day may be the symbolic end of the summer, but peak mosquito season will not end until November in warmer states in the South.

While Zika has yet to spread beyond Florida in the continental United States, public health experts are concerned that it could. (The number of homegrown cases in Florida had reached 56 by Tuesday, according to the Florida Department of Health.)

Officials are keeping a wary eye on parts of the Gulf Coast, particularly Houston — where the tropical, mosquito-borne illness dengue fever had emerged in recent years — and New Orleans.

Puerto Rico, a territory with the largest number of Zika cases in the nation, has taken the hardest hit, with more than 8,700 cases of 16,800 over all.

The vote failed. Now what?

Most lawmakers say money for Zika efforts will ultimately become part of the stopgap measure lawmakers will have to pass at the end of September to keep the government funded and avoid a shutdown. While party leaders continued pressing for their favored stand-alone Zika funding bills Tuesday, they have not ruled out tacking the item onto that broader continuing resolution, where it may find passage easier.

This means health officials may be waiting at least a few more weeks for funding — and longer if Congress fails to pass a stopgap measure at all.