By Jonathan Kaminsky

Oct 4 (Reuters) - Ballot measures to legalize marijuana in Washington state and Colorado gained support this week from a pair of prominent Republicans - U.S. Senate candidate Michael Baumgartner and former Representative Tom Tancredo - who could help sway conservative voters.

No state has ever legalized marijuana for recreational use. The federal government considers it an illegal drug, but 17 states and the District of Columbia allow it as medicine.

Baumgartner, the Republican challenger to Washington state's Democratic Senator Maria Cantwell, said in a phone interview the state initiative, which would allow the sale of marijuana to people 21 and older at state-sanctioned stores, is a "thoughtful way forward."

"It checks a lot of boxes we want to see, in terms of children not being exposed, in terms of not increasing marijuana usage and not allowing it in public spaces," Baumgartner said.

Tancredo, who served five terms in the House of Representatives from 1999 to 2009, this week endorsed the legalization campaign in Colorado. He argued government should not interfere with people's choice to use pot.

In Oregon, a third state where voters this November will decide whether to allow recreational use of pot, the campaign has struggled to find big name Republican supporters.

Legalization opponent Kevin Sabet, a former adviser to the Obama administration's drug policy director, disputed the argument of many libertarians that government should not interfere in pot use by people.

"The libertarian argument is fundamentally flawed because drug use does not affect just the individual, it affects healthcare costs, criminal justice costs that we see with a legal drug like alcohol and costs to our highway safety," Sabet said. (Writing by Alex Dobuzinskis; editing by Mohammad Zargham)

Copyright 2012 Thomson Reuters. Click for Restrictions.

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  • Alaska

    Legalized for medical use. <a href="http://www.flickr.com/photos/alanasise/6847095796/" target="_hplink">Flickr: alana sise</a>

  • Arizona

    Legalized for medical use. <a href="http://www.flickr.com/photos/billward/110338154/" target="_hplink">Flickr: Bill Ward's Brickpile</a>

  • California

    Legalized for medical use. <a href="http://www.flickr.com/photos/gerbache/2260207829/" target="_hplink">Flickr: gerbache</a>

  • Colorado

    Also legalized possession by non-medical users. <a href="http://www.flickr.com/photos/dok1/520845832/" target="_hplink">Flickr: dok1</a>

  • Connecticut

    Legalized for medical use.

  • District Of Columbia

    Legalized for medical use. <a href="http://www.flickr.com/photos/bigberto/2770838680/" target="_hplink">Flickr: ~MVI~ (off to coron)</a>

  • Delaware

    Legalized for medical use. Flickr: <a href="http://www.flickr.com/photos/dougtone/7749689644/">Doug Kerr</a>

  • Hawaii

    Legalized for medical use. <a href="http://www.flickr.com/photos/ricardo_mangual/6006230817/" target="_hplink">Flickr: Ricymar Fine Art Photography</a>

  • Illinois

    Legalized for medical use.

  • Maine

    Legalized for medical use. <a href="www.flickr.com/photos/indywriter/2683524563/" target="_hplink">Flickr: indywriter</a>

  • Maryland

    Legalized for medical use.

  • Massachusetts

    Passed ballot initiative for legalized medical marijuana in 2012.

  • Michigan

    Legalized for medical use. <a href="http://www.flickr.com/photos/kayoticblue/213316452/" target="_hplink">Flickr: ckay</a>

  • Montana

    Legalized for medical use. <a href="http://www.flickr.com/photos/csbarnhill/2633187564/" target="_hplink">Flickr: csbarnhill</a>

  • Nevada

    Legalized for medical use. <a href="http://www.flickr.com/photos/http2007/4699361533/" target="_hplink">Flickr: http2007</a>

  • New Hampshire

    Legalized for medical use.

  • New Jersey

    Legalized for medical use. <a href="http://www.flickr.com/photos/paulflannery/4021996652/" target="_hplink">Flickr: psflannery</a>

  • New Mexico

    Legalized for medical use. <a href="http://www.flickr.com/photos/everyskyline/3134662783/" target="_hplink">Flickr: michaelwhitney</a>

  • Oregon

    Legalized for medical use. <a href="http://www.flickr.com/photos/d-powell/2099638403/" target="_hplink">Flickr: digging90650</a>

  • Rhode Island

    Legalized for medical use. Also decriminalized possession of less than one ounce.

  • Vermont

    Legalized for medical use. <a href="http://www.flickr.com/photos/bryanalexander/6129117/" target="_hplink">Flickr: BryanAlexander</a>

  • Washington

    Legalized for medical use. Also legalized possession by non-medical users. <a href="http://www.flickr.com/photos/rose_braverman/6924724331/sizes/l/in/photostream/" target="_hplink">Flickr: Rose Braverman</a>