What does Slate mean in "Slate political reporter"?

My check on a dictionary turns out this hit:
a list of candidates nominated by a political party to run for election to public offices
It seems not suitable for the context.

Context:

Lewinsky has talked about aspects of the Clinton scandal in the past. In 1999, she published “Monica’s Story” in cooperation with journalist Andrew Morton. There were reports in 2012 that she had signed a deal to write http://www.slate.com/blogs/xxfactor/2012/09/20/monica_lewinsky_s_book_deal_12_million_is_a_lot_of_money_and_yet_we_still_feel_bad_for_her.html, but such a book has yet to appear.
With Hillary Rodham Clinton mulling another run at the presidency, Lewinsky’s new piece is sure to get lots of attention. In some ways, it represents a replay of the era of the late 1990s for a new generation of young voters.
In response to the Vanity Fair news, Slate political reporter Dave Weigel tweeted:

A voter who turns 18 and can vote for Hillary in 2016 was only 2 years old during the Lewinsky scandal. https://twitter.com/search?q=%23math&src=hash https://twitter.com/search?q=%23reporting&src=hash