Lawmakers like Representative Tim Scott, Republican of South Carolina, who advocated for the harbor dredging project with other members of the South Carolina delegation, insist their requests are neither earmarks nor wasteful. “This was a merit-based project that was open and transparent,” said Mr. Scott, who helped secure $150,000 for the first phase of a harbor-deepening project in Charleston, his hometown. The project is expected eventually to cost as much as $300 million. Mr. Scott, a favorite of the Tea Party movement, said he is opposed to earmarks and that dredging the port was in the national interest because it would accommodate bigger cargo ships and help create trade opportunities and jobs.

The Obama administration did not agree and did not include the project in the Army Corps of Engineers budget. As a result Mr. Scott and Senator Lindsey Graham, a South Carolina Republican, who tried to earmark financing for the project last year, threatened in April at a news conference in Charleston to tie up the government unless the project was approved. Mr. Graham also pledged to hold up President Obama’s nominees in the Senate. After the threat by Mr. Graham and lobbying by Mr. Scott and other members of South Carolina’s Congressional delegation, the corps agreed to pay for the dredging.

“Persistence pays off,” Mr. Scott said. “We knew dredging the Port of Charleston was a worthy project, and we were persistent in ensuring that the corps knew that, too.”

In some cases, freshman support for the financing of projects in their districts have put them in opposition to other members of the Republican Party who are calling for deep spending cuts and the elimination of hundreds of federal programs they consider wasteful.