Facing a skeptical and curious audience of liberal bloggers, Pennsylvania Sen. Arlen Specter accentuated the left-leaning side of his long Senate career as he prepares to face Rep. Joe Sestak in a highly competitive Democratic primary.

In an appearance Friday before the “Netroots Nation” annual conference in Pittsburgh, Specter said that bloggers should support his 2010 re-election campaign because he has “a lot of experience, and when tough issues come up and President Obama needs a spokesman to face hostile crowds, I can go out and do it effectively.”

Specter, who’s seeking a sixth term (and his first as a Democrat), touted his support for abortion rights, embryonic stem cell research, an expansion of children’s health insurance programs, the economic stimulus law and President Obama’s efforts to overhaul the health care system and enact climate change legislation.

Specter even referenced his role 22 years ago — when he was a Republican — in scuttling the Reagan administration’s Supreme Court nomination of conservative jurist Robert Bork.