Cutting funding to an organization that provides contraception is a really bad way to attack abortion.
"Pro-life" Republicans are targeting Title X funding, which provides contraception and sexual health advice to millions of needy Americans, and more specifically Planned Parenthood, whose contraception and sexual health services (but not abortion services) are partially supported by Title X. In 2009, Planned Parenthood performed a total of 332,278 abortions (pdf), a number that congressional Republicans apparently find intolerable. According to Guttmacher, however, if the government were to cut all Title X funding, we could expect 406,000 more abortions every year—nearly three-quarters of a million if added to the Planned Parenthood abortions already performed.
Keep in mind that Planned Parenthood only receives $73 million a year under Title X. If Congress decides to cut all of the organization's federal funding, including the $293 million it receives under Medicaid, it would certainly add to the number of abortions performed in the United States.
In short: If you really want to see a lot more abortions, cut funding to family planning programs. Who knew the Republicans were so pro choice?
Update: This post was updated to clarify that the abortions in the chart's right column would be extra abortions.